ostrich

I don't know if this has been discussed already, but I am wondering if anyone with 5AT noticed that they would get different gas mileage with the Sport Shift? The interesting thing is, at lower speeds and in city traffic, I found myself being more aggressive with the Sport Shift, in order to get a faster pick up. That, of course, burnt more fuel. However, on the highway, I noticed that at 70mph, the Sport Shift seemed to be more fuel efficient - the engine was going at less than 2000rpm at 5th gear, while with the regular automatic, the engine would be going at 2500rpm at 70mph.

Has anyone noticed that too? Does it have anything to do with the gear ratio, if there is indeed such a difference between the Sport Shift and the regular automatic?

MikeL

Sorry to say, but I don't think it makes a difference. The 500 rpm "change" that you're noticing is probably the torque converter locking. It does that in auto mode just as it does in "manual" mode, but it depends on throttle input and a whole bunch of things I don't know anything about.

Basically, the sport shift and the auto are the same, only in one instance you're controlling the gears.

Another possibility is that in auto at that speed and that throttle input you're still in 4th. Since there's no indicator there's no way to know besides pushing it over to SS. Try driving at a constant speed in SS and then pushing it over to auto (or vice versa). If you notice a difference then that would be really neat. But no, the two modes share the same ratios.

Hope this helps.

kiteboy

I use SS 95% of the time and it's definitely the torque converter locking. You can feel the TC kicking in as you back off the throttle and see the rpm drop instantly by 500 rpm. Also, the car is definitely in 5th. 4th gear at 70mph would definitely show over 3000 rpm. Another thing to keep in mind is that if the TC isn't locked, you can't correlate rpm with road speed because of the variable slip in the TC.

Here's a good summary of how the TC works: http://howstuffworks.lycoszone.com/torque-converter.htm

In conservative driving, the AT in "D" mode upshifts as early as possible. However, if you put the hammer down, the AT will delay shifts and at full throttle, even waits until redline to shift. In "M" mode, you have the option of early upshifts at any throttle input (and 2nd gear starts). So it's foreseeable that your economy might be better with SS with the right shift strategy.