We were travelling from UK to Italy and stopped here for one night. They do have underground parking but our SUV & roofbox wasn't going to fit through the door. You have to pay for their parking also (6 euros i think). However there was open air parking across the road, pay & display at a reasonable rate. Car park did look a bit sketchy tbh but... lots of other cars using and ours was fine the next morning, yay lol.
Very helpful and friendly chap on reception, room was clean & comfortable and shower was great.
Mulhouse is a great place to walk around with things to see, bars, restaurants etc. And you're only a few hundred meters from the action.
A nice place to stop on our road trip.
We didn't take the breakfast but it looked usual continental style.