3.6 Economy

[Kuhlsnu]

I agree on the 89.. I could tell a performance hit with the 87 and no difference between 91 and 89.

Btw my mileage was about 4 mpg lower than it is now on a mix of highway and city when I first got my car but I realized the dealer only had about 31 psi in my michelins and they take 44psi. Helped out slightly.

[AznPrydeRegalRyde]

My guess is that your Aurora had the 4 spd, 4L60E I think, with the talll final gear. In which case, you would get better mileage in the Olds. A CTS will pull even the 4.0L Aurora after about 30 or 40 mph, thats one of the benefits.

23 mpg on the highway at 65-70 still is pretty low tho.

[Custom88]

The Aurora had the 3.5L V6 with the 4t65E transaxle with 3.27 final gear ratio. The CTS is definitely a LOT faster. I'll check the tire pressure. I didn't even think of that..

[silver bullet]

What ever you do don't put 44psi in your tires.

[wait4me6920]

Here's a succinct blurb from TireRack.com regarding the issue of tire pressure settings -

http://www.tirerack.com/brakes/tech/...jsp?techid=147

[MJDART]

First off milage tested over 2000 miles of driving, 23.2 mpg, averaged during 70% highway driving 65-80 mph. Recently 367 miles on a tank - maybe 1 gallon left in reserve. Spent the last week doing around town driving 90+ temps average 20.4 mpg. DIC indicates 27-28 instant mpg at 70-75 mph

Tire pressures. If I set cold pressures to 31 psig and drive 30 highway miles to work the tires heat up and my pressure increases to 35 psig. If you set tires to 44 psig like Kuhlsnu you may be asking for trouble

[Richie]

Originally Posted by Custom88

I'm into my 3rd week of owning my 3.6 2005 CTS and am really disappointed in the fuel economy in comparison to the Aurora I used to own. The CTS is a lighter car with basically the same size engine and I can't seem to get over 23 MPG on the highway whereas I was getting 27+ in the Aurora. If I set the DIC to instant MPG, it never really goes above 24/25 MPG on the highway @ 65-70 MPH. Is this typical? If it's not, what can I check to see if everything is working properly? The air filter is new, and I don't have any lights on. I see this car has a ridiculous amount of 02 sensors. (5 of them?!)

I had the same concerns as well. I have a new '07 with the 3.6 and the best I've got on the highway so far is 24.8 MPG. It had gone as high as 25 MPG, but dropped slightly as I continued to drive. I had 2 Caddy's with the Northstar V8 engine that got better mileage than that. And my brother has a 2004 Maxima which has a very similar engine to the CTS and he gets over 28 MPG on the highway.

I was pretty surprised how poor the MPG is on the CTS. I think it's mainly due to the weight of the car. The CTS is a pretty heavy car for its size.

So I wouldn't be concerned that anything is wrong with your car. It just doesn't get very good gas mileage.

[Custom88]

I put my tires up to 39 PSI. Hopefully that'll help in the gas mileage department. It surely does ride a bit rougher though. The tires from the dealer were only at 29 PSI!!

[Wrestler07]

39 is way too high

[Jim's 06]

I've got an 06 with 9,000 miles, air pressure 33 psi. Three weeks ago I tanked up, reset the computer, drove thru town, got on the interstate, drove 61 miles at 60-65 mph (10 under prevailing speeds), and the computer was showing 30.7 mpg at destination. Last January I was driving across Oklahoma, had a strong tail wind, so I decided to see what the car was really capable of. I filled up, reset the computer, drove 40 miles at 55 mph. The computer was showing 33.1 mpg at the end (no A/C). Of course, that was a REALLY good tailwind! It got 28.7 at 70 mph across AR/TN/VA, lights on but no A/C. Oh yeah, I always get 19-21 around town, but it drops 2-3 mpg with A/C, in town or hiway. I expect it to drop soon when the "winter gas" comes out.