In answer to your question. I have no idea. It depends on the road laws for both Germany and Denmark. In the UK that would probably be a no no.

I would suggest from the site that any suggestions made or answers given will be peoples own views and cannot be legally viewed and acted upon.

If you or your brother do not do own research for driving the car in any other country and get stopped then this site accepts no responsibility for your actions. I suggest you read up on this and make 100% sure the car is fit for legal road use.

Good Luck with your studies.