I love people who say that letting off the gas doesn't use less fuel. Go find some car of someone with an AFR gauge and watch it when they let go of gas while driving....you'll see it skyrocket to the lean world.

 

What, are you serious?

Pick which one's cheaper? Total brake failure while riding the brakes down a steep grade resulting in you flying off the side of a cliff and dying, or doing what the car was designed to be able to handle in the first place.

Why in gods name would be more stressful for the engine and transmission to do engine breaking then to run at wide open throttle? I'm pretty sure you're going to have more total mechanical stress on the system while accelerating at WOT then you will by using the engine to brake while going down a steep grade, since your rev's are going to be much lower then when punching it on an on-ramp.

I suppose you're going to tell me I should be granny shifting my MT to save the syncros too, and that WOT should be avoided or my "glass" transmission will shatter.

Coasting around in neutral is dangerous. You won't be in the proper gear to accelerate quickly if an emergency situation comes up. That said, I rarely downshift into 2nd unless I'm in traffic. at a stop light I'll go from 3rd to neutral to full stop.

Leave it in the right gear, use the engine to brake. It won't harm your car, and you'll be prepared when something bad happens.