My a8 Audi has 180000km went to back up, my driveway was slippery, and noticed that my engine was revving up but the tires were not spinning . car drives perfect in forward . backs up ok as long as you do not give it to much gas.car has never been abused

We need to know the make and the year and when this car had tune up if you want an answer,all the best.

Although I have no heard of this happening on your particular car, there is one thing.
When the car is warm, have someone who is extremely careful feel the lower radiator hose whilst the motor is running.
Some cars will have a tired and soft lower radiator hose that will suck together when the engine is revved.
This normally does not happen whilst the car is in the driveway, you actually have to have it running down the street, so it would not normally be noticeable just by revving the engine .
God bless your efforts.

Open the screw on the sump under the engine, best to do a oil change after a quick drive as will drain better.

Ask a Dealer or check your owners manual

you dont need a diagram to see the timing marks on the top/bottom pulleys,just clean them off and run a piece of chalk around the perimeter.they are a bit obvious

check the conections on the lomb clean the inside of the bulb holder might be a loose wire or conection if light still on the computer in the car is saying that there is a bulb blown if all else fails disconect the battery for half an hour if its still on pass might need reseting

There is no inertia fuel cut-off switch on your car: 1999 Audi A8 4.2
Only fuel pump relay. See picture bellow - The engine management diagram: (Send me back please your e-mail address if you need bigger pictures)

Owner manual or engine manual. What is your question?

google www audiworld.com, select resources at top of page, select option tires/brakes/ suspension. 4th artical from top of page. A4/ A6 , front control arm replacement. gives full discription with pictures and diagram.

The thrmostat is on the upper protion in the front of the engine, you must first temove the timing belt to access it..Might as well do the timing belt job at the same time.