A tow bar mounted bike rack is a secure option if you've got a good solid tow bar on your car, and the Thule EuroClassic G6 LED 929 3 Bike Towball Carrier is a fantastic alternative to roof mounted racks which can be tricky to load and can interfere with fuel consumption.
Thule are known for producing some of the most impressively engineered racks on the market, with designs for every possible type of mounting option. The 929 Euroclassic G6 is a flagship model, with a good number of bells and whistles and even more available as optional extras.
World's first electric bike carrier capable of carrying two bikes, load capacity is 30Kg so fine for the newer generation of power assists machines but probably not enough for some of the chunkier versions of yesteryear. Neat touches include the tilting mechanism which allows you to get into the boot even when the rack is on the car wider wheel gulleys and an optional wheel ramp so you can ride straight on to the rack… not.