Carrying out:

WARNING: This page is about a different car, the 2003 BMW Z8, 2002 BMW Z8, 2001 BMW Z8, and 2000 BMW Z8. However, it is still accessible from the selected car via links, so may be relevant.

Always conform with the procedures to avoid injury to persons or damage to parts.

On automatic transmission, select "P" setting, apply handbrake.
Move the shift lever of vehicles with manual transmission into neutral and apply the parking brake.
Ensure that the jump leads cannot get caught in rotating parts, e.g. fan.
First connect positive terminals of both batteries with one jump lead (red).
Use positive connection point in engine compartment for vehicles with one battery in trunk.
Then attach second jump lead (black) to negative terminal of donor battery and to engine ground or body ground on vehicle to be started.

CAUTION: Never connect second jump lead (black) to negative terminal of battery in vehicle to be started. This would produce explosive gas which could be ignited by sparks.

Danger of explosion!

After engine of vehicle to be started has started up, first disconnect the jump lead on the negative terminal/ground connection. Then remove jump lead from positive terminals.