Originally Posted by 84_Jetta_GLi
another dumb question: when slowing down, shifting down slows the car, i know what it is slowing the car down, but how does it?
Exactly the opposite of upshifting when you're accelerating. The transmission provides you with different gear ratios so for any given engine speed (say 2000 rpm) the transmission output speed changes. On your car at that engine rpm you will see about 15 mph 1st gear, 25mph 2nd gear, etc. When you downshift AND let off the accelerator engine compression slows the engine and that slows the car.
Let's look at this another way. Say you're going down the road at 50 mph in 5th. If you downshift to 4th and step on the gas do you slow down or speed up? The reason you speed up is because of increased engine rpm even though you're in a lower gear.
I hope this makes sense, if not let me know and I'll try to restate it.