How will you get to the hotel?
I'll go in the car with my sister. (Or "I'll go by car" or "I'll go in my sister's car".)
Where are you going?
I'm just going out for a drive. (I wouldn't say "I'm just going for a ride in the car).
My brother was in the car with his wife when they had the accident. (Not "My brother was riding in the car with his wife.)
Mum, can we go in the car? I'm too tired to walk.