Terrible gas mileage

[Mr. Tasty]

So I have a 1987 325e. I pretty much put only freeway miles on it with cruising at 65-70 mph. I recently put 240 miles for 10 gallons st the fill up. I recently changed my spark plugs, and oil change. I changed with 20w50 because of the extreme Arizona heat. I have a fuel filter that I need to change most likely. I also heard that a clogged cat could cause bad fuel economy and lower power, but it is tough to tell if an eta has loss of power. Anyone have any ideas? The exhaust smells rich. Thanks

[mr.vang]

CEL? o2 sensor usually cause bad mpg.

[MattAvino]

wait, is the 24 mpg the bad mileage that youre talking about? cause that seems fine to me

[Suspence]

Exhaust leaks? What gears do you have?

I have a rebuilt motor, 272 cam, HUGE exhaust leak, a ton of other crap and I'm getting like 20 MPG or so... little less when I drive harder. When I compare that to some of the cars that I work with on a day to day basis I'm OK with it lol.

[mr.vang]

wait, is the 24 mpg the bad mileage that youre talking about? cause that seems fine to me

24 hwy is pretty bad, eta should get at least 30 hwy. 24 city is pretty normal though.

[BoxDriver86]

Had the same issues. Changed my O2 sensor and now I'm getting between 31-34mpg highway with very conservative driving.

[mikeedler]

maybe it's the way you drive. Try to be more like a grandpa on the gas pedal.

BTW, how many miles are you guys getting on an average for a full tank?
I'm averaging about 22 mpg with a 2.7, 288 cam, 3,91 gears-- I think that's o.k. for a car that old. heck, the brand new are only getting bout 30 mpg.

[Mr. Tasty]

maybe it's the way you drive. Try to be more like a grandpa on the gas pedal.

BTW, how many miles are you guys getting on an average for a full tank?
I'm averaging about 22 mpg with a 2.7, 288 cam, 3,91 gears-- I think that's o.k. for a car that old. heck, the brand new are only getting bout 30 mpg.

I told you, its freeway miles, and between 65-70 mph cruising. That is with very conservative driving. Haha, I am not that stupid. I am very gentle with that accelerator.





There are no codes popping up, other than the normal maintenance and oil change indicators. Can the exhaust make that big of a difference? My exhaust pipes are full of bends and smashed sections. Maybe causing too much backpressure? Anyone have any thoughts on the clogged cat and the very "fuely" smelling exhaust?



Oh btw tires are at 29 psi F 31 psi R, just like bmw speccs

[Conki]

22.5-23 mpg with mostly highway driving. I have a heavy foot though and a 3.73 diff.

[LivingLegend06]

Incorrect tire size will throw your odometer off. As a motor gets tired its going to get more inefficient. Unless you have had a recent sudden drop in gas mileage it might not be something that you can easily fix.

My eta averages around 27-29 with mixed driving. I don't think I have had a single tank that has gotten over 30mpg in the ~30,000 miles i have put on it.

[Rsully70sev]

I get 18mpg. Wtf

[5Toes]

Cruise control saves lives.

USE IT

[DrJosh]

My cruise control doesnt work. Around town I get terrible Gas milage. But I have a 5-speed, m20b25, 4.10 LSD, and an exhaust leak. But i did get about 300 miles out of a tank of gas on the highway (drive straight for about 5 hours will do it).

[CabbE30]

I can get 25mpg with my chipped b25 on the freeway driving normal. Oh i have a 4.10 diff also.

[Kershaw]

2 people have stated an exhaust leak in the same sentence as bad gas mileage.

how is that relevant? lol.

i put a brand new o2 sensor in my eta (r.i.p.) and it went from 22-23mpg to 28-29mpg. and it stopped misfiring. i used a 91 mustang 5.0 o2 sensor. only $45.