This analysis is seriously flawed. You consider all the costs -- the development costs, tooling, unit production, and marketing. But you only consider a tiny fraction of the income generated: what consumers paid to buy these cars.
Producing a green car like the Volt was one of the conditions for GM to get $50 billion in government bailout money. Dividing $50 billion by 22,000 cars sold means GM received about $2.3 million per car!
This may well make the Volt the most profitable car any auto company has ever made.