Gani

We have a lot of hills and mountains where I live. So stepping on the brakes when going downhill can wear down the pads really fast. The slopes are so steep sometimes that the Q7 will be doing over 70km/h when I need to slow it down. Instead of stepping on the brakes I always bring the gear down to second. The engines revs shoot up and the car does not sound okay to my wife. I always tell her that it is better to slow down this way than to step on the brakes. Now I am starting to doubt my own opinion. The car does sound stressed when I slow down this way. What would you do guys?

STiGuy

I live in a hilly area and my Q downshifts when it's going down a hill. Depends on the slope, sometimes the rev can go up 4000 or more. IMO that's usually better than relying on the brakes because of the Q's weight. There's not much stress on the engine since it's not under load. But in my case, it's not so good because when I head out in the morning, I don't want it to downshift and rev to 4000 before it warms up. I will try hill descent function and see what it does.

Eppieguy

Hill decent is for off road use, only works up to about 5MPH I believe.

superswiss

Nothing to worry about. For going downhill it's best to put the car in the lowest gear possible so that the car for the most part maintains the desired speed using engine braking. Then when you need to slow down step on the brakes and downshift as needed.

Gani

Maybe the question was not clear....... is it bad when you are doing a high speed over 70km/h to put your car into second gear?

superswiss

That depends. Does the Q7 rev match on a downshift? As long as the engine rev matches and the downshift doesn't result in an over rev, which the transmission won't let you do anyway, then it's fine. If the engine isn't rev matched, though, then you are shocking the drivetrain and not really recommended.

Gani

Sorry what does 'rev matched' mean?

superswiss

Rev matching means that the engine revs up to the rpm for the next gear before engaging the gear for a smooth gear change and no shock to the drivetrain. In a manual transmission this is something the driver does on a downshift before letting out the clutch by blipping the throttle. In semi-automatic transmissions such as the dual clutch transmission (S-tronic in Audi speak), the computer blips the throttle before letting out the clutch and some more modern manual transmissions have auto rev matching where the computer also blips the throttle as the driver lets out the clutch. In traditional automatic transmissions such as the one in the Q7, rev matching has been largely absent in the past, because the fluid coupling of the torque converter absorbs some of the drivetrain shock, but more modern automatics in particular in more sport oriented cars rev match now, too, for smooth and shock free shifting especially when shifting aggressively like you are asking about as to not upset the car's balance.

Gani

Thanks for that... so no more aggressive down shifting for me then

trackvaulter01

Transmissions are expensive. Brake pads are cheap.