Is my bicycle or E-Bike insured on the bike rack on the car?

Yes. Damage on the bike rack is covered, even if the bike can't be repaired afterwards. It doesn't matter whether the car is parked outside the supermarket while you shop or overnight in a hotel car park.

Theft there is only covered, though, if you also lock your bike to the rack with a suitable lock, see "Which bike lock is sufficient?".