So I've started noticing whenever I'm going downhill in my 2010 IS250 and I apply the brakes, the gear increases by 1 and I feel a slight boost in speed then the brakes apply. I know noting about this and was hoping someone knows about this problem so I can try to see what I can do before it could possibly get worse.

 

Are you sure your car is upshifting? It should downshift in the scenario you described.

 

Dont think it upshift. The cpu is made to downshift when going downhill at certain speed while pressing and holding on the brake's. Switch your dash guage thing to see the shift # to determine.

 

It's a feature, not an issue. If you were driving a standard transmission, you would generally downshift to slow down and use engine compression instead of riding your brakes.

When you hit the brake, the car understands you want to slow down and will downshift. I believe it is much more aggressive in PWR mode as well.

 

Are you confusing the RPM with the gear? If you press the Display button on the steering wheel a few times, it'll show the gear. When the gear downshifts, the RPM will increase.

 

Thank you for pointing that out, he may not know how a vehicle operates. Common knowledge and common sense can be rare these days. Lol

 

No the OP is correct. My car up shift's when I am going down hill and (specifically when I DONT HIT THE BREAK) because, in regular drive mode, the car wants to provide optimal MPG. If your heading down hill and you break coming to a stop, the car would downshift and stay in the high RPM because it is still providing optimal MPG's at that point.

Most cars in regular drive mode want to be the best economy for the driver so if you are ever in drive mode and have the display on the gear, you can see how fast the car shifts from first to 6th gear between 0 and 50 mph

 

Mine has always done the same thing on the same steep downhill road on my way to work. It is simply selecting a lower gear to help "engine brake" the car ALONG with you also pushing the footbrake. The car is measuring the angle of the road surface and is proactively helping you in case of an emergency braking situation.