It depends on the car kit.

The Prius has a keypad built into the screen on the dashboard
The Parot CK3100 I put in my wife's car can dial numbers using the
knob on the screen to select the numbers required.
Some car kits will use the phone's keypad - if this is yours - buy a
phone holder that suckers onto the windscreen to hold the phone
steady, similar to a fully fitted car kit.

The features really depend on the car kit.

The Parrot has its own built in voice dialling for phonebook number
which can be stored in the Parrit independent of the phone having
voice dialling or not. Have a llok at parrot's website for more
details.

Tym

~There's no place like 127.0.0.1~