A US-based company named Wikispeed has adopted a modular approach with the design of the SGT01, a car designed as a modular platform which will empower suppliers to innovate freely. Each part of the car is a component that fits into a standard interface. For example, when the engine wears out, it can be removed and replaced in one piece, like a tire. Although they are still seeking funding to go into full production, they have designed a 4-seater commuter car that gets up to 114 miles per gallon and can sell for $20,000 using this approach. Although it's not in production yet, you can still order one today on the internet.
Corrected from an earlier sketch.