In a word, YES. It depends on the car and the ICE system. Mine came with a "pre-equipment pack" which needed a phone-specific interface kit.
The phone slots into a holder which connects to the charger/antenna connector, and works through the radio and a microphone somewhere in the headlining. Pretty good, too.
Some cars now come with a Bluetooth interface - you start the engine, the BT links to the phone in your pocket, and the car system works just like a BT headset would. If it's as good as the Motorola BT headset with my V3, it's going to be brilliant. If it's as bad as the SE one with my previous phone...