Forester - Maximizing Fuel Mileage?

With gas prices increasing by the day, like most people I would like to maximize my overall gas mileage on my 2001 Forester (automatic transmission). Normally, I get about 24-25 mpg in mixed driving.

At what engine rpm does the engine run most efficiently? Although I've slowed down my driving speed, I don't see the gas mileage improving. Around town, I've been keeping it at 40 or under and on the highway, between 60-65.

Also, would removing the roof rack make any significant difference in gas mileage?

Thanks!

Reply to
BRH
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Just went on a road trip with my 2001 Forester. Taking off the roof rack makes very little difference in gas mileage. I also found mileage did not change very much regarding highway speeds as well, our speeds ranged from 60 to 80.

The biggest difference in gas mileage you will find is very dependent on the stopping and starting, ie your driving habits. Do you floor it away from the the light? Do you coast to a stop or jam on the brakes at the last minute? Do you idle in traffic!!!!!????

If you place a very non aerodynamic item on the roof rack, then yes your gas mileage will drop.

BRH wrote:

Reply to
etienne

My 2000 Forester gets ~22 mpg with air on 100 % here in Florida. My best mileage is found when my AT shifts at ~2-2200 rpm and the torque converter locks up at 35-37 mph. I do not force the car to 2200 rpm and let off but, ease up to the rpm. I keep my car in good tune, use major brand gas and run my tires about 3 psig over recommended or

Reply to
Edward Hayes

have a 98 forester 5 sp. once went 400 miles at 60mph and got about 35 mpg. also, i use synthetic oil.

Reply to
joggernut

The new Consumer Reports has a write-up on this very topic. They claim any gasoline engine when going faster than 60 mph uses up far more gas than maintaining speed at 60 mph. The flaw I find here is that they don't mention at what RPMs this 60 mph vehicle's engine is running. Differing gear ratios can make all the difference and should I have a 6-speed, I'm damn well going faster than 60! Back to reality, I dont have a 6-speed but I've had plenty of sticks that vary widely between speed/rpm ratios. Maybe I need to re-read as they may be reffering to an auto but I'd thkn the same idea applies.

Again citing CR, a rack can make about a 5% difference

Reply to
John

Industry standards claim synthetic oils will give 2-5% on average.

Reply to
Jerre Bassler

Synthetic Oil would probably have the most gains for those who make short trips I would think

Reply to
Grolsch

On Sun, 04 Sep 2005 22:44:14 GMT, "John" wrote in news: snipped-for-privacy@comcast.com:

I would take Consumer Reports with a grain of salt.

Consider the following on their web page, amusingly dated Oct 2005:

The problem with new-car models Think twice about buying a newly designed model in its first year

When a new model is introduced, the media buzz and marketing hoopla can tempt you to be the first on your block to drive one home. But this can cost you in dollars, time, and hassle.

I have owned a few new cars, some in the first year of a new model and some in the last year. The car that gave me the most problems was in its last year of production. The two cars that gave me the least aggravation were brand spanking new to the market: a 1982 Accord sedan, and the 6th Acura ever to be delivered in my city.

Since wind drag increases with the square of speed, it becomes significant more quickly. Stick your hand out the window. At

50 mph you can start to feel something. By 70 you have to be careful how you shape your hand. By 120 you'll have trouble doing much with it. Below 50, the gas engine isn't very efficient because it hasn't been designed to be. It has too much available power. You only use about 15hp in the average small car at 60 mph to maintain a constant speed.

But to state that going over 60 is far more wasteful is too vague a generalization. How about 62? Far better advice is to suggest people travel at a speed that is close to normal speed on that road for safety, but as slowly as practical for best efficiency.

I've done many long trips where the speed during the day was fairly constant. At about 50 mph I get 40% better than the overall yearly combined mpg, and about 27% better at 70 mph.

Different engines are designed to run at different speeds, so unless you know the engine design, the rpm isn't going to tell you all that much. A corvette running at 1600 rpm at 60 mph eats more than my car at 3000 rpm at 60.

The number of gears doesn't tell you much either, since most

6 speed transmissions, auto or manual, are designed to be more closely spaced ratios than a 5 speed to keep the engine in the power band. The top gear is often virtually the same ratio as it would be in a 5 speed or even a 4 speed auto.

Maybe one thing we'll see on newer cars is a taller top gear for fuel efficiency with much lower revs at highway speeds. I would assume most manufacturers don't like to put too high a ratio because it makes the car rather slow to respond. Ideally there should be almost no power left to accelerate the car - you should be using almost full throttle to keep a constant speed.

Reply to
Dave Morrison

The consumer reports claim is simply rubbish. You can design a gasoline engined (or any other type of engine) vehicle to be at its most efficient at any speed you like, whether 30 mph or 300 mph. It's all a question of the power available and the aerodynamics and what other compromises you want to make.

This, for example, gets 39.5 mpg (3.8 gal/hour) at 150 mph with two people (at sea level -- it gets better at higher altitudes):

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Reply to
Bruce Hoult

Do you actually have a roof rack, or do you mean the cross bars which are mounted on the roof rails? Either way, yes. Get rid. You should never leave the cross rails on when you are not using them. Weight makes a difference as well. Don't caryy stuff around in your car that you don't need.. Also, check your tyre pressures regularly and make sure they are up to pressure. Running low tyre pressures will imact on fuel consumption.

Biggest difference you can make is with driving style. It used to be believed that gentle acceleration was the best way to go, but research in recent years shows that it is much more efficient to accelerate briskly up to your cruising speed. Anticipatory driving is most important. Leave big gaps to other traffic, keep your concentration levels high and think well ahead. That way, you can avoid losing momentum.

All of the above can make a difference of two, three or even four mpg, which is significant on a long journey. To measure your consumption accurately you will need to brim your tank to a point where you can actually see the fuel every time and record the precise fuel quantity and exact mileage. Don't rely on rough calculations or onboard computers, which won't give you an accurate enough figure for your purposes.

David Betts snipped-for-privacy@motorsport.org.uk

Reply to
David Betts

I totally concur with you on that one. I took a chance a while back and bought (new) one of the first 1984 Dodge Caravans. In addition to being a brand new model, it was a new concept from a company that was close to major financial problems. Other than normal wear and tear items like brakes & shocks, tune ups, I had no significant problems till it was over 190,000 miles when I had to replace the auto trans. I traded it in at 230,000 and even at that point the 4 cyl engine barely used any oil.

Reply to
ZZ

Foresters really suck on mpg then. My 04 outback never gets less than

  1. Usually averages 24-25 with one long trip getting 28 . I have the K&n filter and only use full synthetic oil. Tires usually @ 32psi all around
Reply to
bigjim

IF the transmission doesn't jump out of overdrive too often, them it might help. For example, I used to manage a fleet of Chevy vans. I noticed that they would drop out of overdrive with the slightest increase in load. The next batch I ordered with a higher ratio differential. Dealer said the engine would run faster and use more gas. I disagreed. I was right. The transmissions stayed in overdirve longer and average MPG increased 8%. Pretty good for a fleet!

One fuel economizing device that should be brought back is the vacuum gage.

Reply to
Steve Bukosky

Air resistance is the enemy. Calculating the power needed to move down the road, air resistance is a cube function, every time you double the speed, the power requirement goes up 8x.

An engine is most efficient at the speed that max torque is achieved. The secret is to find the best compromise between high engine efficiency and min wind resistance. Stop and go driving, rapid acceleration and heavy use of the brakes are hard on fuel consumption.

Mickey

Reply to
Mickey

Actually - current equivalent weight synthetic oils probably don't have any better fuel economy characteristics compared to modern conventional oils of the same viscosity. Friction reducers in all modern oils make the frictional losses from oil neglible in regards to fuel economy. The primary difference when it comes to fuel economy is viscosity.

Most multiviscosity conventional oils will thin down as their VI improver shears, which can increase fuel economy. However - this may not be ideal for long-term engine protection.

Now there are some really thin synthetic oils (0W-20, 0W-30) which can be designed for superior fuel economy chararcteristics compared to a typical 5W-30/10W-30. It's currently not feasible to make an API rated conventional oil in those weights.

Reply to
y_p_w

Don't use the brakes! Slow down by cruising as much as possible. If you use the brakes to stop from 80 mph in 100 yards instead of lifting off the gas half a mile back then you waste all the fuel that you used to maintain your 80 mph for that half mile. That's about a fiftieth of a gallon (5+ cents) each time. You migth not stop very often, but the same applies to corners. Oh, and engine braking is just as bad as brakes from this point of view.

I find that if you can use the same pump at the same station then the auto-cutoff is quite consistent. Even different pumps are quite close, usually. The main thing is to fill it yourself so that you can prevent an attendent from "helping" you by topping off some random amount manually.

And if all else fails, the total fuel put in over a number of sequential tankfulls will get more and more accurately measured in percentage error terms.

Reply to
Bruce Hoult

WRT cutting the engine off at a red light: Won't the extra gas used at each start-up offset the amount saved when shut off, especially for 30-45 seconds at a red light?

Reply to
Mike Lloyd

Apparantly 30 seconds of idling uses twice the gas of a restart (electronic fuel injection), so theoretically 15 secs is enough to start saving gas (and reduce emmisions). Starter wear may be a factor, but these aren't Fords (or GM or Chrysler) so I don't expect problems. I think the main thing to remember for saving gas is Drive when you NEED to and choose alternates whenever available or wait to combine trips. Also always try to preserve momentum, it's that initial inertia that kills the MPG's in the City.

Reply to
Grolsch

oooh..."you got a K&N?!?!"

Wooooowwwwww!

...did the sticker give you an extra 5 MPG??!

...oh---Hi Jabaria!

Reply to
CompUser

heh, mine gave me ~2, but I guess I could be driving differently, but don't think so.

Reply to
Dave - Dave.net.nz

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