Last post on Oct 20, 2006 at 3:12 PM
You are in the Cadillac STS/STS-V
What is this discussion about?
Cadillac STS, Cadillac STS-V, Fuel Efficiency (MPG), Sedan
#10 of 16 Comment on axle ratios/fuel consumption
Jul 22, 2005 (7:24 am)
A test of the STS with 1SE package resulted in performance that was very close to that of the 1SG package. That is not to say that the higher performance gearing will not "feel" better. Running the engine at a higher speed does not result in equal increases in fuel consumption. To cruise at a particular speed requires a certain amount of power. Running the engine at a higher speed will increase the power output of the engine, so the throttle will not be as wide open with the higher performance gears at any one speed.
As far as the EPA rules go, the STS is one model/series, whereas the old Seville was two models (SLS and STS), so different numbers were published. The AWD STS has a different number. I think that it would be easy to rate each axle ratio that is available, but this does not seem to be done. The 2005 Corvette offered a high performance gears for both the automatic and manual transmissions, yet there is only one set of EPA numbers for each transmission...
I have a book on the 84 Corvette that shows the fuel consumption in different gears at various speeds. At 70 in third gear (1:1), the MPG is just under 20 (~19+), while in 4th (0.7:1), the MPG is just over 25 MPG. The engine is running 2000 RPMs in 4th70 MPH, and about 2800 in 3rd. The engine speed is more than 40% more, but fuel consumption is about 25% greater.
#11 of 16 My 2006 STS
Apr 30, 2006 (6:35 am)
Just wanted to go on record to say that my 2006 STS is great. I got it in blackwith the black leather interior, and the luxury performance package. Sound system is five stars, performance and acceleration fantastic, etc. The engine doesn't even wake up until its at 80 mph, and is ride is smooth as your road surface. I have about 2500 miles on it now, mostly suburban driving, and overall mileage has crept up to 20.3 mpg. Its not as frugal on gas as I'd like, but I'll bet it will do a lot better on an upcoming interstate road trip. I think the engine is overkill for around town.
#12 of 16 2007 EPA MPG
Jul 20, 2006 (3:57 pm)
V8 w/6 speed manumatic = 17 / 27
2006 was \ is: 17 / 26
Hoping for a bigger 'bump' in highway mpg
( sigh )
#13 of 16 Re: 2007 EPA MPG [rayainsw]
Jul 21, 2006 (10:41 am)
Not knowing what the axle ratios are (at least I don't), it is hard to make any judgement on the results. However, after seeing what the six speed did for the Corvette, the results seem about what I would expect. They (EPA) did not list an AWD V8, nor are there any SRX listings yet. If the axle ratios are unchanged from last year, then the results are for the 2.73:1 ratio. The AWD results would be for the 3.23:1 ratio. The six speed should improve performance, even with no axle ratio change, although the 3.42:1 axle ratio was already too low to improve acceleration. I think with the new transmission, a 3.08:1 axle ratio would be closer to optimum.
#14 of 16 Re: My 2006 STS [coolguy]
Jul 26, 2006 (9:33 am)
It's to have a "beater" to run around town in and just keep your "ride" for more extended highway driving. I have a BLK/BLK 18" tire STS V-8 also. The car is powerful and very NIMBLE. I agree the STS is a GREAT car EXCEPT for the "murderous" depreciation factor.
Oct 20, 2006 (11:01 am)
OK, so a year has now passed, and if anyone can update now with how their STS is performing mpg-wise I would like to know. I am really close to pulling the trigger on an 06, and the preference is the V-8, for power, but if it is going to be a gas glutton I might opt for the V-6 since my wife will be getting the car anyway. Any updates would be helpful. I just hate to trade a solid 00 Eldo that gets 31 mpg on the highway, and has two years left on an extended warranty, for something that won't do near as well. Info on true mpg from a six or two would also be welcome. Thanks.
#16 of 16 Re: Gas mileage [bigmike5]
Oct 20, 2006 (3:12 pm)
2005 1SG AWD. My mileage was terrible, than began improving after about 10 thousand miles. Me or the car? I don't know for sure. I get about 18.5-19 m.p.g. on mostly (70%) highway driving according to the car's mileage computer now. At first I was getting about 13.