We are travelling from Barcelona to San Sebastian to Madrid and back to Barcelona.

By bus, it will be roughly 90 euro total each person.

Will it be faster and maybe not too expensive for 4 people to rent a car? How is gas and all that mileage? Does anyone think we could all pay 100 euro each for a car + gas in order to get to these 3 cities? Is parking a hassle? I think it is in Madrid but Im not too sure.

Need some insight here! Thanks!