Might be taking bikes to France this year, but someone told me that the french Police have been cracking down recently on UK cars arriving in Calais carrying bikes with strap-on racks.
As I understand it, tow-bar racks are fine because they mechanically attach to the car, but the strap-on ones aren't considered suitable.
The rack I've got is a Thule 3 bike one, and so long as it's been attached properly is pretty bomb proof - I've done hundreds of miles with three bikes on the back this way in the UK. Our family car (a Chrysler Grand Voyager) has a tow bar and electrics, so I could go out and get a tow-bar version, but I'd just like to clarify the rules first.
Appreciate I'll need a lighting board/number plate either way.