Just got an 07 STS-4. Love the car but my gas mileage is not much better than my truck, and nowhere near the posting on the window sticker. Even at 55-60 with cruise on and no air, 23mpg is the best reading I can get, but who drives 55? I average about 18 coombined highway (70%) and city (30%). Anyone else notice this type of mileage? BTW- the AWD is supposed to only shave 1 mpg off the non AWD.

 

How many miles on that motor, it will get better as it breaks in, but honestly I get about 11 litres / 100 km or 23 mpg in my Deville on the highway and I thought that was excellent. I don't keep track of it in my truck, but with a 170 litre tank it seems like it goes forever.

 

all that Katz said plus on a car that size, tire pressure can make a big difference.
what type of fuel are you running?

 

Hey Gunzee

My 07 STS has 1100 miles on it. I just took a a 150 mile round trip and only averaged 23.0 mpg. I'm hoping that it's because it is still breaking in. Tire pressure set at 32 cold. Just me and the wife with 2 lightly packed suitcases. Average speed around 70 mph with air conditioning on. I thought it should have done a little better too. I have just rear wheel drive. My 01 Deville gets 27MPG on the same trip. However city driving on the DeVille was14mpg and the sts is giving me 16.0 to 16.5. I'll keep you informed as to my mpg progress. Going on another trip this weekend.

Eddiek

 

way too easy ..but .. are you guys setting the trans to overdrive?

 

Stomper

If we are supposed to be using a different a shift selection than "D" I'd like to know what it is. The selections are
P R N D. I would assume that D automaticaly uses over drive. It's a 5 speed automatic. There are no other selections that would indicate an overdrive setting.

Eddiek

 

Just took a 350 mile trip and still only 23 miles to the gallon. 1400 miles on the car now. I also had an added bonus. The hood popped open at 70mph on the trip home on the Ohio turnpike! The hood prior to that hadn't been opened for days to check the oil. I know it was closed because I did it myself. If I hadn't closed it properly it would have popped on the trip down and I would have had a warning message. Scared the s--t out of us. I'll inform my dealership ASAP. Maybe an adjustment?

Eddiek

 

Forgot to mention it only popped at the first notch. pulled over and closedit. Whew!!

Eddiek

 

99 sts n* always at 25 to 26 hgh trips...... with good conditions and running speed limit......????????? i think the sts did 27.? that was one time.... "the conditions"..wind at our backs, and mom was in the car......hehehe
all in all remember your driving a fat ride with a great American V8......how nice..... lets not complain........ whats a few bucks?$? dont ya love it?
rickyd

 

Rickyd

I'm only running a 3.6 v6 in my STS. Like I said before, my 2001 Deville N* got 27 mpg on the highway. Maybe it's still to new at 1400 miles.



Eddiek