SoCal240/6

What wear will it cause? Well, it WILL cause additional wear to your transmission components, driveshaft, CV joints, clutch (if its a stick, automatic transmission clutch packs if its an automatic) - basically your entire drivetrain.

If you don't plan on keeping the car past the warranty period, no big deal. (Just don't advertise your habit amongst knowledgable car folks, you'll embarass yourself).

But if you are planning on keeping the car long term, the habit of downshifting to slow the car down (to avoid brake dust and extend your cheap brake pad's lives) is not a smart habit. Brake dust can be washed off and brake pads (and rotors) are cheap.

BlackC230Coupe

The Owners manual does not say not to down shift to slow the car down during the break in period. It just says the transmition is not covered by the Mercedes-Benz Limited Warrenty.

I would never use the transmition to slow my car down that much not to use the breaks. I would not wanna put that much stress on the drivetrain. To me i hate the break dust but its ok because i wash my cars so often.

aborwick

I found touch-shift useful passing trucks on I-76 (the Pennsylvania Turnpike), which is an old mountainous highway with narrow lanes much construction, and many trucks. I would shift from "D" to "4" and gain torque to quickly pass.

avlis

That's exactly right. Just because it's an automatic doesn't mean it doesn't wear out. There are bands, gearsets, and clutches in that thing!

I was tought that engine braking was to be used in cases where you want to MAINTAIN a low speed without RIDING the brake (where the brakes could overheat). Such as when you are going down a long hill. Using the tranny/engine to slow the car down is asking for trouble. Brakes are cheap compared to engine bearings, and transmissions.