what i did in order not to transfer numbers to sim:

i started the pairing process in the car, but instead of searching the car from my phone, i choose to send contacts (all) via bluetooth.

the phone found the car (the car was in BT pairing mode, remember?) and i chosen to transfer all the numbers into the car.

it worked with e53 ericsson t39m - but it might work with other cars/phones.

no harm in trying