Gas Mileage Issues

[Xcobra]

If you had a bad exhaust leak, you would know it because your car would be very loud.

His diagnosis doesn't make any sense.

There's no way that your car is on it's last legs. Unless it runs like crap, has no power and smokes like a mosquito fogger, but I'm guessing that's not the case?

You don't have any check engine lights? This may sound silly, but is your check engine light burned out? It happens.

Actually, the check engine light works just fine. The car runs smoothly to be honest, I am just out of ideas in terms of what I can do to figure out what's going on. Regardless, it's an old car. I am just tempted to just deal with it at this point.

do the math on the mileage and report to us what you get

I have a little less than a half tank left. Once it gets to a quarter, I will refill and do the math.

 

[Eli]

Age/mileage doesn't matter if the car is maintained.

I pulled an 89.0MPG 51 mile round trip in Insight #2 the other day. Not bad for 443,000 miles.

 

[Doppel]

The best way for you to do this is to go fill your tank to full now and weight until the pump click. Don't squeeze more in. Then run the tank down near empty and keep a tab on how many miles it was until, when returning to the same gas station, it fills up again. The smaller the proportion of tank and miles the greater the variance. If you do an entire tank you'll know confidently what your real MPG are.

 

[LTC8K6]

You would hear the engine get loud if you had a leak at the exhaust manifold. You would certainly know if those joints were leaking badly.

Are you sure he didn't say intake manifold? An intake manifold leak could let extra unmetered air in.

 

[JCH13]

Do a full seafoam treatment and see what happens to your mileage.

 

[Meghan54]

Do a full seafoam treatment and see what happens to your mileage.

^This.....among other things.

Again, low mileage use cars face unique challenges, such as wearing out parts faster than higher mileage/more frequent-heavier use cars. A low mileage/low use car really never heats up properly and can really tear up plugs, O2 sensors, etc.

Not to mention, if the car's being used in a lot of stop-and-go traffic, it's facing one of the worst wear cycles you can subject the vehicle to. Given it's 12 years old and its usage pattern, not surprised to see your gas mileage slowly drop off a bit over time. Unavoidable.

 

[hanoverphist]

You don't have any check engine lights? This may sound silly, but is your check engine light burned out? It happens.

i used to work for a small family owned used car lot back in my teen years. that sucker was a schiester. he would disconnect the CEL if he couldnt easily fix the problem. finding that out the same week he told a mech to rip out the guts in cyl 8 on a camaro so he could sell it without any engine noise were the reason i quit. i always check to see if the light pops up at ignition before buying a car now

 

[lostatlantis]

If you haven't done so, go to autozone or advanced auto parts and get them to do a free reading with their OBD reader. Even if the check engine light is off, there might still be a code in the memory.

But yeah like someone already pointed out, the gas gauge might not be perfectly linear. For my 96 firebird, the needle actually goes 1/8 or so past FULL with a full tank of gas, and I've determined after many tanks of gas/mileage calculations that the first 1/2 on the gauge is actually more like 2/3. Definitely do the gas tank mileage calculation a few times to get a better feel. Just reset your trip odometer next time you fill up, and then write down the number at the next fillup.

 

[punjabiplaya]

Do a full seafoam treatment and see what happens to your mileage.

^This.....among other things.

Again, low mileage use cars face unique challenges, such as wearing out parts faster than higher mileage/more frequent-heavier use cars. A low mileage/low use car really never heats up properly and can really tear up plugs, O2 sensors, etc.

Not to mention, if the car's being used in a lot of stop-and-go traffic, it's facing one of the worst wear cycles you can subject the vehicle to. Given it's 12 years old and its usage pattern, not surprised to see your gas mileage slowly drop off a bit over time. Unavoidable.

make sure to aim it at a neighbor you don't like (in case you don't know what seafom is, read this, then watch a youtube video)