Originally Posted by wstar

I really don't recommend switching back and forth between D and M constantly. It's a really confusing way to drive, and makes it hard to predict what gear you'll land in during the transitions. I use the M mode pretty much exclusively, but if you've never driven a manual before you'll need to learn some new things, like watching the RPM gauge and knowing when you want to shift.

The 7AT will protect you from most stupid mistakes (it won't let you downshift low enough to exceed the rev limiter, and it won't let you stall out the engine by upshifting or staying in too high a gear as you decelerate). As noted above, it will let you sit on the redline if you fail to upshift in time though, which is pointlessly abusive if you do it.

For those with the 7AT that have only driven a plain automatic before, I'd suggest setting aside some time on a back street somewhere with no traffic to acquaint yourself with shifting.

From a dead stop, put the gear selector in "M" (the gear indicator on the dash will show "1" for first gear), then put your hands on the wheel so you can reach the paddle shifters and take off slowly at light throttle. Accelerate up to somewhere around 4-5K rpm, then slowly let back off of the gas pedal and watch the revs fall as the car stays in gear and slows down. Now do it again, but use a little more throttle and click the upshift (right) paddle when you get to about 5K rpm, you will now be in second gear, and the revs will drop off to a lower number. Don't let off the gas when you shift, just leave the gas pedal steady. Accelerate (again, not full throttle, you're trying to learn) up to about 5K rpm in second, then pull back on the gas a bit and decelerate through second a bit. When it gets down around 2.5K rpm, click the downshift (left) paddle. The car will shift back down to 1 and the revs will blip back up to a higher value.

You get the idea from there. Play with upshifting and downshifting. Keep an eye on the gear number indicator and the RPM gauge, and learn how it works and how it reacts. Pay attention to what you're doing with the gas pedal too. You'll notice some pretty dramatic effects on shifting speed and engagement force depending on whether you hold the gas steady, push it in more, or let it off, in the middle of a paddle-click.

At any given speed, you usually have 2-4 reasonably valid gears to choose from that will result in different engine speeds (RPM) at the same wheel speed (MPH). Choosing a lower gear will make the RPMs higher, choosing a higher gear will make the RPMs lower. Generally speaking, the lower you keep the RPMs, the more fuel efficient you'll be. The higher you keep the RPMs, the more power and responsiveness you'll get from the engine. Higher RPMs also increase engine wear to some degree, and increase oil temperatures. It's all a tradeoff.

When you're in the D-mode all of this is being done for you by the computer guessing your intent from the position of the gas pedal. Gas pedal held lightly = it goes to the highest reasonable gear it can to save fuel. As you push the gas pedal in deeper, it downshifts to give you more power. The problem with D-mode (on all automatics) is that the engine has only the current speed and gas pedal position for information. It has no idea about all the other things you know that affect what gear you want to be in (like that turn coming up 60 feet down the road, or that you're going to pass someone in about 3 seconds, etc). Also, if you rely on D-mode doing the downshifting for you as you push in the pedal, it's hard to predict exactly when and how much it will downshift. You don't want to be "surprised" by the downshift engagement in the middle of a corner for example. It's much better if you control the downshift so that you know what to expect and can compensate accordingly at the steering wheel.