Any of the ones that use seatbelts to secure them. Just put a rolled towel in the 'bucket' underneath and a towel or blanket behind to protect the leather.
We're on our second seat now, having gone from a Maxi-Cozi to a Römer seat for up to 18kg and now using a Cybex 2-part one which will convert to a booster-seat next year.
The current one uses the car seatbelt around the kid, so is unsecured when not in use. The Römer had a 4- point harness and used the seatbelt to secure the seat itself. To secure it more fully, I used a seatbelt tensioner which was the best £10 spent imo...