Originally Posted by PhoenixMr2

I can't believe you guys haven't figured this out yet.

This is caused by the emissions standards we have in this country. Almost all DBW cars do this now. When moderately heavy on the gas if you suddenly come completely off the gas the car is tuned to burn off all the gas that has already been injected into the head/intake manifold (depending on car). It's not much gas, but it is plenty to maintain rpm's for a second or two or even to make the rpm's jump when the clutch is put in.

This has happened on every DBW car I have driven (that is fairly new). My '09 Wrangler does it, and I noticed it in a '08 WRX, a '07 Civic, and a Genesis Coupe I test drove. I didn't notice it when I drove the 370z, but it was a 40th edition and it only had 15 miles so I didn't want to ruin someones future baby by driving it hard.

Try loading up the engine in 5th gear with fairly heavy throttle then jump off the gas and wait for a second or so then put in the clutch... you should see the revs hang or possibly even jump.

Again, I've been told time and time again it is an emissions control device where the car burns off all the gas that has already been injected to avoid it just moving through the engine un-burned or partially burned and emitting worse emissions.

I'm sure if I could find some articles on it online somewhere (I seem to remember even edmunds mentioning it), but I'm heading out the door to visit family out of town. I'll post more info later