06 fuel mileage

[06 black prix]

hi everyone im new to the forum my name is justin. i tried the search but no luck mabe someone can help me out. i have a 06 with the 3800 n/a and it gets terrible gas mileage. (like 18 mpg) just wondering what could cause this? the car does mostly interstate driving. i have heard that the thermostate going bad can do this but everything seems normal, the heater works normally and the car seems to run great. its hard to tell what the temp guage is reading because it has like no numbers on it(usually sits like half way up or a little less)the car has 70000 miles.

[01gtspecial]

18 city or highway? thats pretty good for city. u should get atleast 25 or 26 hwy

[TheOtherNick]

Check the gap on the plugs see if they are getting worn out. Have some one hook up a scan tool to it and check the 02 sensor.

[06 black prix]

mostly interstate driving (75-80 mph) with this car. idk it just seems like it should get better mileage, my 93 chevy 4wd pickup can get 18 if im nice to it. that thing wheighs like 5 or 6 thousand pounds. not sure though im pretty new to the newer stuff. ill check the plugs in the A.M.

[ZR1Vette09]

try driving 70, those extra 5 miles above that make a HUGE difference. try 70 for a week and see if you still have problems.

[Poil336]

probably not that much though. i still get 27ish doing 80, normal's almost 30 for me on the highway doing between 70 and 75. if there's no SES light it's probably just little things. like he said, plug gaps, you could look at the O2 sensors, MAF even, but you'll probably have a code for that. check your air filter, oil, even transmission fluid. a high engine temp can be a good indicator of something not running right, if it's more than 160-180 when you're driving then something needs fixed. what kinda rpm's are you getting? 80mph should be something like 2600ish i believe

[Neanderthal]

I had a 2002 Regal LS 3.8 and high 20s low 30s was normal for the highway.

The above advice sounds good, could be any of a number of things. Where are your tire pressures?

IIRC our Regal ran about 35 MPH/1000 RPM, it was a serious loafer on the highway. Final drive was either 2.93 or 3.05, don't remember. Probably 3.05.