What do most of you folks do? You guys do the usual put it in neutral and use the brakes to slow down the car, or do you downshift? I ask this, because I would assume downshifting lowers MPG because of the rpm's spiking up on a downshift.

 

I always downshift any chance i can get (it makes the car sound meaner haha) unless its a sudden stop then i just pop it into neutral.

I'm not positive but i was always under the impression that downshifting was better for MPG but i am not certain???

 

Wait, are you just putting it in the next lower gear and slowing letting out the clutch? That isnt good for the car. If your heal toe downshifting (blipping throttle to match rpms), then it wont hurt the car but as for your question im not sure.

 

Downshifting does lower mpg, and can sometimes put stress on the engine. I'd rather wear out the brakes.

 

The engine is not meant for braking. That is really bad for the engine.

 

Really?!?

 

Yeah, using the engine to slow the car is really bad for it.

Why I downshifted for 90% of the stops I made on my 93 Grand Am, for over
100,000 miles, and I had to do zero work on the tranny and engine.

Downshifting to slow down is so bad, you'll see every trucker use lower gears
on a hill to avoid wearing out their brakes

Seriously though, using the engine inertia to slow down or hold a lower speed
won't hurt your car unless you overrev it. You may lose 1 mpg.

Matching revs on a downshift is unnecessary, our transmissions are synchronized so rev matching isn't needed.

 

Whoever said downshifting is bad for the motor is ignorant and uninformed. You know, all the JDM racers you hear about, they just use their brakes and keep it in the same gear to stay in their powerband...

But anyways, all i wanted to know is if it hurt mpg, from the revs spiking up. Thanks for your input Patton, it seems youre the only poster with knowledge on this thread...

 

truckers have to downshift on hills..... there is so much weight to stop that the safest way to actually stop is to downshift, not to mention they are running huge, huge turbo deisel motors that do get checked out much sooner than commuter cars.

but yes... obviously downshifting does affect mpg, higher rpms mean more gas and air is needed for faster combustion.

 

i down shift all the time. never had any issues with any of my cars.

 

When using compression to slow the car, there is little gaz coming to the intake; else the gaz/air mixture would make the car accelerate/not decelerate. Therefore, my view is that mpg would not be negatively affected by downshifting.

 

the only bad thing i can see about downshifting to slow down is the possibility of someone rear-ending you... You'd be surprised how ignorant most people are, often times if people do not see brake lights they wont slow down...

 

a little off topic but just curious, when you guys revmatch, do you match precisely 100% of the time? I seem to be a little off at times like 100~300 rpms off.

 

O im sorry for me being unimformed about downshifting. The whole racing world must be stupid also. Ask anyone that actually knows how to drive a performance car and ask them if they downshift without blipping the throttle. I have been racing cars for awhile and my father races professionally in grand am, so I must not know anything about downshifting. We dont do it constantly or anything.

 

Umm who said you HAVE to heel toe downshift?