EVERY possible thing that could cause low mpg?
 

What's up guys. So, I feel like my mpg is horrible. Under normal driving conditions, my mpg is around 12-13 mpg. I want to know EVERY possible thing that can cause low mpg, large and small, so I can get to the bottom of this, and fix the problem.

Under inflated tires, bad O2 sensors, dirty MAF, dirty air filter, dirty throttle body, failing camshaft sensors, heavy foot, failing cats, fouled/old spark plugs, clogged injectors, lean fuel mixture, too much weight being hauled in the car, Windows rolled down over 40mph, AC turned on, bad alignment, heavy rotating mass (I.e. aftermarket wheels), excessive miles on current oil, faulty evap system, leaking gas tank, forgot to put your gas cap on, Street racing, downshifting, driving too fast, driving too slow, Jack rabbit launches, pulling a trailer, blow-by, faulty ignition coils, a cat sitting on your roof, oil that's overly viscous, a stout final drive, high resistance tires (summer tires), not waiting an hour before driving after you eat, an exhaust system (aftermarket) that's too open for the needs of your power band, picking up fat chicks, running from the cops, smoking meth, listening to Motorhead, and buying Arco gas.

Any questions?

Damn....can't possibly add any more to this thread other than that post

I bet it's the cat sitting on his roof... :bowrofl:

Haha great answer, thank you ! . where do I start..?

Just go one by one from that list and knock them out. Keep the fat chicks around though for days when you need to go hoggin.

One thing not on the list was a vacuum leak. I was getting shitty gas mileage and after I fixed that leak it jumped up from 10-12 to about 17-19.

But what is really considered "low"?

My understanding was that 14-ish was considered fairly common city mileage and 19-20 was considered fairly common highway mileage...especially for the AWD sedan.

well i got a fairly consistent 16 to 17 MPG on all city driving. i had an 04 g35 coupe with intake, spacer, headers, and a tune.

Anything below 16 is low for me. Unless you are always gunning it and driving like you're Fast and Furious, the manufacturer estimates of 17-19mpg city should be easily attainable. I average 20mpg with all city driving since I usually take it easy and shift around 2k.

For starters, get proper tire inflation and clean air filters. Remove any unnecessary weight/junk from the car. Drive it normal and keep RPM's below 3k.

If you're still getting low mileage after than, then its one of the others on Scrag's list

As has been suggested, let's ask 'what is low?". Therein lies the philosophy of where you want to be. Let's just make (for example) this idea that you got exactly what the factory told you you'd get; 26npg. Is this sufficient? If you aren't a 'settler' then it's really not. The question is not where do you start, but rather 'where does it end..?'

Optimal fuel efficiency goes hand in hand with optimal HP, optimally reading sensors and optimal conditions. You must be truthful with yourself. And with us. Haha

If I try, I can hit 24-26 MPG on the highway. But I need to actually put the effort into trying to achieve this.


If I just say "f it" and drive the car, I find that my mixed mileage tends to settle around 16-17 MPG when I pull up the nav computer screen with the info.


Most of the time, I just say F it. If I wanted fuel economy I would have bought a prius.

The car sucks on MPG. I ride highway and cant get over 20 MPG

Damn, I feel better about my Sedan. I get around 22 mpg on mixed driving. The best I've gotten on mixed was 23.5 mpg. I haven't had a chance to do any all freeway driving yet so I think I could hit 26 mpg then.

Wash & wax your car to make it a little more aerodynamic. That's about the only thing not covered in ScraggleRock's reply.

Ha!!