big depreciation is not related to the cars. There is a $7500 federal tax rebate on a new electric car, so the moment you drive it off the lot, its blue book value drops an additional $7500. In addition, different states offer credits from of up to $5,000, and unless you take the car out of state, that amount will also drop off the value. This is the primary culprit for the huge depreciation numbers, but there is more.
 Perversely, people with higher incomes don’t get California’s $2,500 credit, so for them, buying used is a very wise idea, because somebody else got the credit, and it’s reflected in the price of the car. Of course, if you are rich enough, you may tolerate paying $2,500 more than everybody else for the new car. In fact, if not for the sales tax, it would be a good strategy to get somebody else to buy a car for you and get the credit, then buy it from them. Or take over a lease (getting to that…)

via David Levinson.