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What's your gas mileage? What helps?


bonus12

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tell what your mileage is and make sure you say what model and trim you have!

 

recently i am getting in the low 40's, but i have been on an upward trend since i bought the car 7 months ago. i drive a crx HF.

 

i noticed an increase after putting STP Fuel Clreaner in a few tanks.

 

also, check out this website where you can get EPA ratings and log your mileage data!

 

www.fueleconomy.gov

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I usually average about 30mpg highway and 28 city w/ some highway. I baby'd my car last tank and got a tad over 33mpg highway. By baby'd I mean, always shifting at around 2500-3000 rpms and setting the cruise on 69mph on the interstate. For 3 mpg I decided I'd rather drive the way I want with the cruise set on 75mph.

 

Throwing a couple ounces of acetone in the tank on a full fill up for about 2 tanks usually gets me a 2 mpg jump for the next 8 tanks following. Really helps clean the intectors and fuel system out. Don't reccomend that every single tank, but very small portions, in small increments is really beneficial IMO.

Edited by HungGSR
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Wife gets 41-43 in the 93 del sol s with no modifications to the car at all. only get 35 when I drive it tho...o:)

 

I was getting 33-34 in the 95 DX Sedan, after removing the entire AC system it jumped up to 38.

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I'm getting similar gas mileage to Hung with my new sol, which is kinda buggin' me since I got better mileage out of my S model (now I have the Si). Prolly need a tune-up to get it back where it should be.

 

I did the same exact thing as Hung where I tried to get the best possible mileage out of my car by babying it and it only gave me about 2-3 extra mpgs. So I came to the same conclusion -- just drive like normal.

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Never really monitored it in my Rex, but on my Civic I've gotten as high as 41, and as low as 29. Depends on the driving you do, and the time of the year. Summer is going to be lower due to A/C usage.

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I'm getting similar gas mileage to Hung with my new sol, which is kinda buggin' me since I got better mileage out of my S model (now I have the Si). Prolly need a tune-up to get it back where it should be.

 

I did the same exact thing as Hung where I tried to get the best possible mileage out of my car by babying it and it only gave me about 2-3 extra mpgs. So I came to the same conclusion -- just drive like normal.

 

That's strange that you don't get better gas mileage than me. My Del Sol VTEC with the B16 was getting around 32mpg highway average. I would think the Si model would do better than the VTEC model.

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BTW, the 41-43mpg I noted above was with AC blasting. The Sol S model rocks as a commuter car. Looks and drives a hell of a lot better then most anything else that gets 40+mpg and it has targa top too!

 

Some recent cars I owned:

If I babied my 94 Cherokee I got 18mpg, if I raped my Cherokee I got 18mpg.... huh It was a 6cly 4x4

The 99 lude got 30 if I babied it, but I usually got about 18-20 with the way I drove it.

The 98 Accord EX was around 30-35, but on flat highway trips we would get close to 40

My current 95 Ram 2500 gets 12... :(

My 86 Monte Carlo with a custom built 350 10.5:1 comp pistons, 4 barrel Edelbrock, Weiand aluminum intake, blah blah, blah, made around 350hp and I got 5 omg -I drove it from my parents place near lake Erie to Columbus (125miles) and had to stop mid way to refuel....but that was back when 87 was only $1 a gallon and I could afford to piss money down the carburetor.

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I live 9 miles from my job and the wife picks up the kids.

 

I ride my 2006 Masi 27inch with carbon fork Road Bike to the office at least 4 days a week, so mpg doesn’t concern me as much as it used to.

 

On average I get 24.67 mpg in my 1997 Honda Accord EX-V6.

 

To get that number, I averaged 6 iterations of the following process.

I would fill up the tank, hit the trip meter, and drive for a week; then fill up at the end of the week at the same pump at the same station. If the pump handle was not changed in that week, the shut-off valve in the handle was assumed to be reliable enough to put the same volume of fuel in my tank as the beginning of the week. I would print my receipt and use the volume (5 significant digits) and the trip meter (4 significant digits) to get the 24.6x, then averaged all six to get 24.67.

 

24.67 is low, but now I only make short trips to the grocery store and long trips to participate in triathlons. If I have the bike on top of the car (Thule rack system), the mileage is noticeably lower; similar to the difference between A/C on and A/C off but not as severe.

 

The wife drives a 2007 Pontiac Vibe (Toyota VVT-i inline 4 cylinder) that gets about 34.5 mpg on average. The car is rated at 32/36 and it seems to be closer to 36 than 32, although I have never measured it using the above method.

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I live 9 miles from my job and the wife picks up the kids.

 

I ride my 2006 Masi 27inch with carbon fork Road Bike to the office at least 4 days a week, so mpg doesn't concern me as much as it used to.

 

On average I get 24.67 mpg in my 1997 Honda Accord EX-V6.

 

To get that number, I averaged 6 iterations of the following process.

I would fill up the tank, hit the trip meter, and drive for a week; then fill up at the end of the week at the same pump at the same station. If the pump handle was not changed in that week, the shut-off valve in the handle was assumed to be reliable enough to put the same volume of fuel in my tank as the beginning of the week. I would print my receipt and use the volume (5 significant digits) and the trip meter (4 significant digits) to get the 24.6x, then averaged all six to get 24.67.

 

24.67 is low, but now I only make short trips to the grocery store and long trips to participate in triathlons. If I have the bike on top of the car (Thule rack system), the mileage is noticeably lower; similar to the difference between A/C on and A/C off but not as severe.

 

The wife drives a 2007 Pontiac Vibe (Toyota VVT-i inline 4 cylinder) that gets about 34.5 mpg on average. The car is rated at 32/36 and it seems to be closer to 36 than 32, although I have never measured it using the above method.

 

i am impressed with you're method.

 

usually i record the amount of gas purchased to 4 significant digts. i don't always go to the same pump.

 

i let the tank run out, leaving about 2 gallons in the tank, then a fill 'er up. i also use the tripometer. i think it's the best method.

 

have you tried recording your data using www.fueleconomy.gov? they offer a nice system and they graph it for you, which is pretty cool.

 

i'm glad to hear you ride a bike on most days b/c that helps the environment.

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Not sure how much it helps as I do not remember the exact numbers, but you get better gas mileage if you refuel when the temperature is cooler and if you refuel more often (such as not going below 1/2 tank)

 

When the temperature is lower the fuel is more dense so when you pump 10 gallons of fuel you are actually receiving more fuel mass. So make sure to fuel early in the morning or late at night, but you would get the best results in the morning after everything has cooled off. You should do this anyway as the cooler morning and evening temperatures do not allow for as many fuel vapors to escape and it is better for the air quality.

 

When fuel in your tank is used up the space that it did occupy is replaced with air. The fuel tank is a closed system though, which is why the tank hisses when you unscrew the cap sometimes as it is equalizing the pressure. It is not perfectly airtight, so it should only do that if you burned up the fuel faster then what the air could leak in around the cap. Anyway, as you use the fuel in the tank you are slowly creating more airspace in the tank. Fuel will only evaporate to a certain saturation level in the tank, but as more air slowly leaks in to equalize the pressure more fuel evaporates to maintain the saturation level in the air remaining in the tank. i.e. if you use a tank of gas slowly and you run it all the way down to nearly empty you are allowing the maximum amount of fuel to evaporate into the air and when you open the fuel door to refill that fuel saturated air is forced out of the tank and into the atmosphere.

 

As a side note, the gas station companies have realized this some time ago. If you take notice, may newer modern fuel stations have nozzles that have a rubber boot on the end of a special nozzle that creates a seal with the opening of the gas tank. What they are doing is recapturing the fuel saturated air that is coming out of your tank. Not only is this better for the environment, it is also better for their pocketbooks as they are able to reconstitute the fuel and resell it back to you.

 

EDIT:

 

I was well as all of you probably hate unsubstantiated claims. I am working on finding information to back up my claims above.

 

Hot Fuel Expands

Turn Down Hot Fuel (btw, their premise of their lawsuits is a complete hoax, but thier science is not. Even if you don't care about when you refuel, you end up gaining back all lost mass of fuel in the winter that you did lose over the summer months.)

 

I keep editing, this is about the 6th edit. I was just idly thinking that we drive with the top off on the Del Sol a lot, since the weather is nice. I wonder if the gas mileage loss from having the top off is offset by the fact that we are usually cruising on deserted country roadways at about 45-50 (instead of flying along at 65-70)?

Edited by x3772
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I do not purport to be an expert in hydrocarbon chemistry, but I would like to say that I agree with your points, and would like to add two more for some thought.

 

“When the temperature is lower the fuel is more dense”

 

This is correct. But the advantage is a matter of 1/10 of a gallon. My information comes from NPR Car Talk, June 23, 2007 (you can go to NPR.org and download a transcript of the program). The reason the change is negligible is that the fuel tanks are buried in the ground where the soil acts as a heat sink. This heat sink is able to regulate the fuel temperature to a certain extent. Your right in that there is a bigger difference in the ground fuel temperature in winter vs. summer relative to morning vs. afternoon. There just is not enough time in the day to heat the ground enough to make a difference greater than 1/10 of a gallon. However, the density of fuel becomes an issue in severely cold whether. I have read articles regarding this topic, and I was shocked to discover that in Canada, the gas pumps have thermometers that correct the meter on the pump for changes in ground temperature. On Car Talk, the consensus was that to be fair, fuel should be sold by the pound (or kilogram).

 

“cooler morning and evening temperatures do not allow for as many fuel vapors to escape and it is better for the air quality”

 

This is totally correct, the California regulations on pump handles (the rubber boot) should be evidence enough that some people care about their air quality and that said quality is affected by gas tank emissions.

 

 

Here is my contribution:

 

I disagree with maintaining at least one-half capacity in the fuel tank. The weight of gas contributes to the consumption of gas. As the tank empties, you car weights less and therefore consumes less fuel. Again, this is another tip that does not make a huge gain in economy. From ‘www.fueleconomy.gov’, the following supports my statement:

 

“Avoid keeping unnecessary items in your vehicle, especially heavy ones. An extra 100 pounds in your vehicle could reduce your MPG by up to 2%. The reduction is based on the percentage of extra weight relative to the vehicle's weight and affects smaller vehicles more than larger ones.”

 

Consider a full tank of gas, in most Accords this is 16 gallons. Since the density of gas is 7.4769 pounds per gallon (737.22 kg/m3), 16 gallons is roughly 120 lbs and a half tank is about 60. This means that the added efficiency of half vs. full is roughly 1.2%. Since 1.2%, even over a year, is not very significant, I would like to add another tip for fuel efficiency. Again from ‘www.fueleconomy.gov’:

 

“Aggressive driving (speeding, rapid acceleration and braking) wastes gas. It can lower your gas mileage by 33 percent at highway speeds and by 5 percent around town.”

 

This statement was tested on Discovery Channel’s Myth Busters and found to be true. Let me apologize to all the aggressive drivers out there in advance (since I share the road with cars when on my bicycle), but more than getting gas in the morning or driving with no weight in the car, this apparently makes the biggest gain in gas mileage; 33% is HUGE.

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All agreed. The findings on the 1/2 fuel tank are all preliminary testing and is a very new concept. I wish I could find the article that was reporting this. As of the release of the findings independent studies had not yet been completed to verify if the laboratory gains from the 1/2 theory outweighed the decrease brought about from the added weight.

 

I knew about the underground fuel tanks being relatively slow to adjust to ambient temperature. If only for the vapor reasons this is still a good idea. Although it is probably minuscule the temperature of the fuel entering the car would most likely be a slightly different temp then the fuel in the holding tanks, but maybe not enough to account for a noticeable difference. I fuel first thing in the morning anyway, its more comfortable to be outside and its just better for the air quality. So if it does help the fuel mileage in some fashion then that is just an added bonus.

 

Since this thread seems to have a few extra environmentally conscious people in it maybe I can get a few opinions on running a vehicle without an alternator. I have been researching this and people are reporting gains of 10% or more (much more in small engines) in fuel mileage. What I haven't been able to determine is if the mileage increase is offset by the additional effort required to recharge the batteries. The biggest proponents of this are for drivers that drive shorter distances infrequently. Using a deep cycle marine battery in place of the normal car battery they are able to have around 80-100 mile ranges without the alternator. The most efficient method for recharging was through the use of a small solar panel mounted on the roof of the garage (panel was the size of a cookie sheet and cost something like $200) that would recharge the battery in about 2 days. Otherwise you would have to use a battery charger that plugged in and your electric bill may be higher then what you are saving in fuel.

 

An alternative to this would be to simply disengage your alternator belt for 3/4 of your driving and reattach it when your battery depletes to a certain level. What I haven't figured out is what the drawback is on this and why I haven't heard about people doing this at the track. You wouldn't save any weight since the alt would still be in the car, but you would remove the drag from the crank pulley and free up a little extra power to be used elsewhere.

Edited by x3772
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Disengaging the alternator is done at the track. I believe the technique is to run the alternator to sandbag a few runs and then to loosen the belt or remove the alternator belt to win once the vehicle is slotted into a particular category.

 

The problem with automotive batteries is related to chemistry. I have a BA in Chemistry with a minor in Mathematics. I know exactly why an automotive battery acts the way it does when it is discharged and also know that to explain exactly why is very tedious and lengthy.

 

In short, the automotive battery does not respond well to being discharged completely. When we kill our batteries and are unable to start our cars, this is because the potential difference across the posts is too low to start the car, but the battery does actually have voltage. In fact, the voltage present in the battery (chemically) is often sufficient to start the vehicle, but the ions dumped into the battery acid as the battery is used prevent current from flowing freely through the acid. The resistance builds as the battery is used. By disconnecting the alternator, the ions that prevent the free flow of electrons are created rapidly and in such a fashion that recharging the battery does not completely reverse the chemical equilibria in favor of battery functionality.

 

The rapid discharge of an automotive battery is analogous to a deep cycle.

 

Using marine batteries in automobiles is a novel idea, using solar cells to recharge is awesome.

 

When I finished my degree, the big thing was multilayer solar cells utilizing ZnMnOTe. Rather than one p-n junction, the multigap technology uses several stacks that absorb several wavelengths rather than the standard crystalline silicon (1.1eV) which is only about 25% efficient. The multigap is up to 50% efficient. Right now the materials for multilayer solar cells cost more than the electricity they produce. Even if you did want to spend the money, I think you have to have Berkley or MIT “cook” some p-n junctions up for you.

 

Check it out:

 

"Diluted II-VI oxide semiconductors with multiple band gaps," by Kin Man Yu, Wladek Walukiewicz, Wei Shan, and Jeff Beeman of Berkeley Lab, Mike Scarpulla and Oscar Dubon of Berkeley Lab and UC Berkeley, and Piotr Becla of MIT, appeared in Physical Review Letters, 12 December 2003.

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wonderful. Nice to talk with someone who has more to say then "that sounds like a stupid idea"

 

the current goal is to try and get the del sol to 50+. while retaining the option to take the car on longer trips as well. changing the alt and batt setup seems like it would be a good start to achieving that goal. I will need to do quite a bit more testing and research, but it looks like a multiple (maybe two to three) battery setup might be the trick. If I recall correctly one person reporting on this had a setup similar to this in his Metro and was ultimately obtaining 70+ mpg (via this and other mods) and had a range of 80 miles with the single battery. The wife commutes 78 miles every day. So a single battery cuts it too close, as she may get stuck in traffic, or have a storm come in the requires the headlights. The 78 miles does not account for her going for a lunch or an errand either. The trunk lid of the del sol makes for a mighty inviting place to mount a solar cell as well, although it would be much more likely that a couple of them mounted on the garage roof would be what we did.

 

All of this is important to us because she has a hefty commute to work and adding in traveling we put 25,000 miles or more on the primary car every year.

 

I have been doing research on turbos to increase fuel mileage as well. Preliminary reports from numerous sources indicate that a very small turbo setup running at 2-4 psi helps to make more efficient usage of the engine and actually improves mileage a considerable amount. At the same time the very low psi has minimal effect on the longevity of the engine.

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When Honda introduced their Turbo motorcycle in the 1980’s, the claim to fame was that the 750cc engine had the horsepower of the 900cc engine and fuel efficiency of the 500cc engine; all that with a 2 inch thick centrifugal compressor. So I think it is totally do-able.

 

I tried to get some help locally for a similar project and was often be looked at as an oddity. The performance shops in Jacksonville, FL are not really sure what to do with someone that asks what hardware is available to boost the output of a 2.7L V6 from 170hp to 200-270hp while increasing the mpg from 24.67 to 30-35mpg.

 

Your right about the amount of boost needed, and the great thing is the small turbo manifolds are very inexpensive.

 

Another huge advantage is provided by Honda, VTEC-E. Coupled with a VTEC control unit and fuel management system, the valve timing can be held in the efficient mode longer.

 

For my application, the fuel management system seems the best place to start since my V6 is non-VTEC. With the right tweaking, I want to cut the fuel supply to my engine down to keep it just over a stall. The idea came to me when I had a vacuum leak in my 1987 Honda Accord LX (A20A1 2.0L SOHC CVCC 12 valves) that caused to shut off at low rpms; e.g. sitting at traffic lights. I saved a TON of gas letting my car shut down at a full stop. The vacuum issue inspired me with another idea, a way of doing the above without having to turn the key to start it back up. Imagine a Honda non-Hybrid that shuts off at 0 mph (similar to the Toyota Prius), and springs to life when the gas is hit. A throttle by wire system and the right ignition coil coupled to a good processor should be able to manage the task.

 

But again, I have plenty of ideas based on sound concepts, but lack the hardware experience to know what is out there available to the public. In my view, anything that has to be fabricated or is “one off” would present a low level of usefulness as only a select few would have access to the technology.

 

I know the ignition control presents unique challenges that would potentially prohibit their application to older Honda engines such as mine.

 

Something as simple as switching to carbon fiber hood and trunk lid seems like simple ways to cut weight down on my car. Two problems: the quality of the products I have seen is questionable and I do not like to draw attention to my car and have yet to see a good automotive paintjob on top of carbon fiber that did not have a Ferrari logo.

 

 

 

Another tip I forgot to mention: Switch to low weight oil (i.e. 5W30). It lets the motor run more efficiently at start up.

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  • 4 weeks later...

I've heard of the "get gas when its cold" theory. I agree that it helps to some extent like James Mateu said. And I agree that breaking fast, accelerating fast, does give you much less gas mileage as I have even experienced. I had a Toyota Supra that was 6 cylinder Inline and powerful. I always drove fast on the highways, accelerated fast, etc and so I paid the price for that.

 

Currently my 98 Jeep Cherokee Sport gets 24 miles per gallon on the highway (tested it out while driving down to South Carolina from WV) and 18 in the city. Of course that is subject to how I drive.

My old Honda Civic CRX I would estimate gets about 35 mpg on highway and in the city and only has a 10 gallon gas tank. Very good economically though. I usually spent $25 bucks to fill up once every two weeks and that is with the prices of gas at $3 a gallon!

My 1990 Toyota Celica gets 40 highway and 35 or less city depending on how I drive.

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I get anywhere from 35-55 in my 90 Si with a B16A swap and royal purple in the tranny and engine. I did put the stock wheels back on and I noticed that I do get more miles to a gallon if it is over a half tank...

 

I think the reason i get such good numbers is because I have a few mods to my car, so it has a bit more torque and the gears are really short, so i'm in 5th gear A LOT

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From your comments, I would be willing venture that your stock tires are narrower than whatever tire you had on your car before.

 

As your tire’s contact patch is narrowed, rolling resistance is reduced and top speed is increased. The reduced rolling resistance increases fuel efficiency.

 

55 miles per gallon is…unbelievable. You have to share exactly how you achieve this.

 

Please list all your modifications and in excruciating detail.

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