Most car kits or different and aimed at specific phones.
That said, the bluetooth kits are compatible with any bluetooth phone from
any manufacturer.
If you need the phone in a cradle which also charges the phone while you
drive/talk, then you need a car kit that accepts the cradle and a phone for
which a cradle is made.
The N70 does NOT have a cradle, nor does the N80. The 6280 does (but is a
cheap tacky phone IMO), and the 6680 does, which I have recently purchased a
second one of purely to keep my car kit cradle.
Nokia are doing badly in this area. They expect people to buy their phones
and use them with car kits on bluetooth - what about those of us who want to
charge it too and don't want a cigarette charger? We need a cradle.