Help Me Get Better MPGs

[blageo23]

My winter beater (1998 Subaru Legacy GT 2.5l) gets 18-19 MPGs. That SUCKS! My moms Mountaineer(that I was driving) gets that much. Anyone have some tricks to get better MPGs? I was going to replace the fuel filter, maybe make an intake with a K&N, And I also have a fuel system cleaner that I won at the dyno day. The car has new plugs and wires. Anything else I could do?

[Pushit2.0]

Driving style, look up the EPA on your car, if you are close then there is not a hole lot you can do.

~John

[FattyBoomBatty]

skinnier tires that are properly inflated (check yours anyway). You can also add aero mods like flat underbody panels and a lower air dam (an add on, not a whole new bumper).

A really helpful thing to do is simply slow down. Don't accelerate so fast and cruise at a lower speed. 55mph save an assload of gas. I remember a year ago when I drove behind my cousin's truck in my quest. he was pulling a trailer and wouldn't go over 60. I was dying cause it was taking so long, but it took less than half a 20 gallon tank to drive to fargo, where it would normally take almost 3/4 tank. the difference between 80 and 60mph is huge for milage.

[blageo23]

Edmunds says 21/26MPG. I dont accelerate fast cuz im afraid the trannys or engine is going to blow up! The car has 250000 miles on it so maybe thats a reason for the decreased MPG.

[FattyBoomBatty]

could be. change trans fluid and engine oil to synthetic ones that are low viscosity. if the drivetrain has less resistance it will take less power, therefore less fuel to drive.

[Pushit2.0]

Accel fuel uses a lot, if you stab the gas or are not smooth then you will see a drop in milage, if I drive my honda rev matching down shifts I only get ~26mpg but driving like a grandma and smooth with the gas pedal I get ~33mpg. New cars do not have Carbs but still need to put in more fuel with fast throtle movements. Check the exhaust, the cat might be clog, my honda has a cloged cat and when I do not have exhaust leaks it will not even get to the rev limiter.

~John

[JET]

With that many miles you are probably getting a lot of blowby, which hurts mileage. Slowing down is the only thing that is going to make a substantial difference. It isn't worth really spending any money on mods, you won't get the money back in gas saved. T

here are a few free things, inflate the tires higher than the car calls for, but not above what the tire says on it. Let off the gas early when you are going to stop and coast for a ways. Any time you are on the brakes, you are wasting gas. Obviously you still have to use the brakes, but try to limit their use. Driving slower is probably the biggest thing. You could always just buy a different car too. I had a $250 92 Sentra that got 38 mpg, it paid for itself in a few months.

[FattyBoomBatty]

I had a 50 dollar chevy malibu and I paid more in gas and a fix-it ticket than the whole car, so that wasn't cool, but the car was sweet. I'd look for a new beater with a <2.0liter engine.

an old golf or scirocco or something will get great milage. I know my scirocco would get 28mpgs on average and that was with messed up fueling because a sensor wasn't connected! lol. it probably would have gotten 30 or more otherwise.

[blageo23]

The car has a brand new cat from napa(car came without exhaust or cats so I bought a universal car) it also has brand new o2 sensors. I only paid $900 for the car and another $900ish fixing it.

[Pushit2.0]

unplug 2 of the fuel injectors, one on each bank, it will run ok but not have a lot of power, and possible use 1/2 the fuel.

~John

[iceminion]

Originally Posted by Pushit2.0

unplug 2 of the fuel injectors, one on each bank, it will run ok but not have a lot of power, and possible use 1/2 the fuel.

~John

Thats funny, I was under the impression that a car, any car, would be most fuel efficent running at 20% throttle on all 4 cylinders rather then 40% throttle on half dead cylinders.

Who knows! you might be onto something, just like that DEI guy

[xveganxcowboyx]

Originally Posted by Pushit2.0

unplug 2 of the fuel injectors, one on each bank, it will run ok but not have a lot of power, and possible use 1/2 the fuel.

~John

On a four cylinder?


My stepfather has a newer legacy with the 2.5 liter and pulls high twenties or even thirties on the highway. He usually cruises less than 65 on the road he usually drives, but can still get high twenties even at 75 or eighty. Your gearing might be steeper though, which would hurt your high speed mileage some.

The tired engine may be the culprit. Any compression numbers?

[blageo23]

Too much work to do a compression test .

[Pushit2.0]

Its a flat motor, we had a subaru on the dyno that made just about 1/2 the power it was supposed to and to our suprise it was only firing 1 cylinder on each side.

~John

[xveganxcowboyx]

Good to know. So apparently the boxer design keeps things rotating nicely eh? That's really cool.

And I hear the PITA argument about the compression test. I get annoyed just *thinking* about working on one of those.

Originally Posted by Pushit2.0

Its a flat motor, we had a subaru on the dyno that made just about 1/2 the power it was supposed to and to our suprise it was only firing 1 cylinder on each side.

~John

[Andrew7dg]

Originally Posted by Pushit2.0

unplug 2 of the fuel injectors, one on each bank, it will run ok but not have a lot of power, and possible use 1/2 the fuel.

~John

yeah you are joking on that right?... because the cylinders that aren't firing will be adding drag on the engine making it less efficient.

Back on topic.
take as much weight out of the car as possible. Stuff adds up in weight in a car.

And I agree with driving at closer to 65. Even in my DSM manual it states to get the best MPG, drive 55 miles an hour. I got 23-24 with mine with very conservative driving this winter. However I like my dsm so the next tank of gas went down pretty fast.

[Pushit2.0]

Joking on all but the fuel used, the car did run ok, it was just 1/2 the power it was supposed to be.

~John

[niterydr]

Originally Posted by Pushit2.0

Joking on all but the fuel used, the car did run ok, it was just 1/2 the power it was supposed to be.

~John

"Ran okay" meaning it sounded okay, afr was fubar and the car was weak on power.
But it is hard to but check a boxer motor to see if they are off. If you don't know how they are suspose to sound exactly, they can be off.

I have my tires over inflated in my nissan and drive like a grandma most of the time, 33-36mpg FTW!