Architectural Designs Carriage House Plan gives you parking for 3 cars on the main floor and a fully-functioning apartment with almost sq. on the second floor. Only I'd make at least 1 of the garage bays living space too.
Drummond House Plans - - One bedroom suite garage apartment with open concept and cathedral ceiling
Drummond House Plans - - Garage with apartment, 2 bedrooms, open floor plan, screened-in balcony