Hi all. Hoping to get some feed back and realsitic estimate of what my fuel economy should be.

Over the week end I took a short drive to brother in laws place who lives near College Station for free a/c repairs. I did a mapquest search to determine roughly how long the drive is. The round trip was a total of 160 miles.

My problem is that I used an entire tank of gas for a trip that was primarily highway driving. For a car that is completely stock, that seems a bit excessive. The car has new plugs, cap/rotor, ignition module, ignition coil, tires, cats, water pump, alt, brakes(4 corners) and a few others here and there.

Am I expecting too much fuel economy from my car? I know that new, the car was to get about 25 MPG highway, so I would have expected to use maybe half a tank? What do think guys/gals?

Any ideas on what what cause such poor fuel economy?

 

you should still get about 25 highway, so something isn't right, check for codes.
scan it & see what the engine temp is when fully warmed up, see what the INT & BLM numbers are, check the O2 sensor to see if its working right.
on my last road trip i got 29.7

 

What was your mileage then? Around town, short trips, I'm just shy of 16mpg, averaging low to mid 15s, yet mine in 90% stock. Even with my mods, they are more free flowing, than performance "enhancers". Air foil (installed bythe previous owner), K&N, Magnaflow cat, Magnaflow LS1 cat back, relocated IAT....That's it really.

I'd love to hit 20mpg!

 

Hey there Denn_Shah. If I recall, your Monte Carlo has a TPI. If so I would love to get the same MPG as you. My car really is a looker, not a runner. I don't street race or track race, I just want it run strong, as it should, yet docile enough to drive daily.
I understand general mechanics, but I don't know how to check an O2 sensor or how to read BLM's and such. Can you explain it to me in newbie terms so I can take a stab at it. Oh, I don't have any check engine lights on. To add, the EGR is new(AC Delco).

Stephen, to answer your question, the city MPG is not much different than yours, which strangley is not much different that what I am getting on the highway :0(

 

yep, i have the TPI monte, not much has changed on my car other than a little better exhaust with some fake flowmasters. i still haven't done any body work, im looking for a good hardtop for cheap to replace my T-tops with.

both of you should be able to top 20 highway.
no codes is good, but if you have never replaced the O2 sensor or its more than about 2~3 years old, its probably weak but works good enough so it doesn't set a code but can still cause poor fuel mileage. if it is old & you go ahead & replace it, get a A/C Delco sensor, the after markets O2 sensors
don't work as good as they should & can cause problems.

to check the BLMs & the O2 sensor you need a scanner of some kind.
if you have a laptop, you can either buy or build a cable to connect to the ALDL under the dash to see what the ECM & sensors are doing. there is also a program thats needed, but its cheap, free to download & use, he does accept a $30.00 donation which registers the program & gets rid of a 10
second nag when you first start it up each time.

with my in town driving i get around 14~18 depending on how hard i get on the gas from a stop.
when i got my 700R4 in i got around 20~21 highway, which for you would have been around 8 gallons of gas on your trip.
i got into chip burning & took care of a few minor problems so the ECM would work like it is suppose to & got up to 22~23 highway, a few more small changes in the chip got me to 25 MPG highway.
its taken me some time to get it where it is now. that 29.7 MPG trip was pure highway, with A/C & crusie control on running mostly around 65~70 MPH with a few minutes up around 80+.