The E60 does not have an option for a timer on the keypad lock. One can explicitly lock it or not, but not have it autolock after x minutes.
One can set the security lock to come on automatically after X minutes - so this appears to be an alternative - but it is not so useful if you are often using the phone in the car.
If the security lock is on then one cannot get the car kit to make outgoing calls. This is intended behaviour - you have locked your phone so that no one can use it to make outgoing calls - that is what the security lock is for.
If the keypad lock is on and security lock is off, then the phone will let the bluetooth car kit initiate outgoing calls.
Pity that there is not a timer for the keypad lock - so that I don't accidentally make phone calls from inside my pocket when I forgot to relock the phone.