when should i downshift? at a certain speed or at a certain rpm? and if so which ones?

 

Don't downshift and hit the red line (see owners manual on what speeds you can downshift at)... thats about all u have to worry about. However in the 5AT, you don't have to worry about downshifting too much because the computer in the car will only let you downshift so much.

oh yeah, if u have a 5AT, don't let go of the gas when you downshift (if you want to go faster)

 

I assume you are referring to a manual transmission?

Gosh, I don't even think about that anymore. It comes seemingly automatically to me. I listen to the engine and note what speed I'm going, but I never pay attention to specific RPMs.

Perhaps the manual says something?

 

You just need to learn your car dude. One day after you do, you'll see someone else post a thread like this and just laugh You'll know when to shift by how she feels and sounds.