What is really friendlier to the environment - the Prius 2009 or the Lotus Elise 1996

Everybody appreciates the Toyota Prius as being one of the most green car of the century. Even myself who prefers light fast sports cars to family sedans, am impressed of what Toyota engineering built with this car. But is a Prius really that ecological? When you look at it from a full life cycle point of view then you must include the production as well as the removal of the car. I recently read that the gasoline equivalent of the energy needed to produce a Toyota Prius is roughly 1'000 gallons or 4'000 liters of gasoline. That's a lot. That means that only after driving 80'000 km (at 5 liter per 100 km) you have consumed the same amount for driving as for building the car. Or if you assume that you save 2 liters of gasoline compared to the car the Prius replaces (i.e. a first generation Lotus Elise with the Rover K engine) then you need to drive the Prius for 200'000 km until you have made up for the production effort. It might have been more "green" to keep the Elise and to not buy the Prius! So in many cases even older cars may be the better option for the environment than the new green cars. But it gets worse if you reach the end of life with a Prius. There's so much stuff in the car that can't be just easily re-used or burnt (for example batteries) that the overall balance of buying and using such a car may actually not be the best thing to do for the environment. But there's this image and self marketing aspect to it too - George Clooney probably didn't think that far ...