Thanks for that Lutz as we will be passing through Germany in July enroute to Slovenia/Croatia accompanied by Max our border collie.
We do already have him restrained with a harness which latches into a rear seat car seatbelt. In fact we've just bought a new harness from Aldi last week. Max can stand up, turn around and lie down on the back seat but he is otherwise safely restrained for everyone's sake.
I can never understand how anyone can drive around with an unrestrained dog in their car. I would not want to be hit by "flying" Max in accident nor would I want him leaping about barking at other dogs, cats, etc. It's, also, rather unfair to an unrestrained dog in accident.
Regards
Tim