Paul Homewood has a very useful comparison between the cost of the electric Nissan Leaf car and a couple of super-efficient Ford Focuses. The electric car turns out to be a much worse buy. But looking at the costs of motoring to the consumer, and the tax costs can be complex, so there are a couple of points that I would amend.
First is that the £5000 rebate on an electric car is relevant to the buying decision. Otherwise it would not be in place. The purchaser of the car ends up paying £5000 less, so that is a reduction in both the depreciation and the borrowing they will face. As a result the annual cost differential on your figures reduces from £3200 to £1350. However, due to the differential in maintenance this figure is more like £1700.
Second is the difference in tax revenue. New cars attract 20% VAT. For the Leaf this is £4750. After the rebate, the exchequer gives out £250. VAT on the focus Focus Diesel is about £3300. In 3 years, the net tax revenue on the Leaf (purchase price, 5% VAT on electricity, 20% VAT in maintenance) is £50. On both Fords it is £5100.
The figures, by chance, fall out the same. Buy a Nissan Leaf instead of a Ford Focus and both you and the Exchequer will be about £5000 worse off over three years.
The differences do not stop there. As AC Osborn rightly points out there is a problem with range. The Leaf is limited to about 100 miles before a recharge of over four hours. As such, for families, it becomes a second car, whereas the a Focus with a range of at least 400 miles and a five minute refill can both serve for the school run / daily commute and for longer trips as well. An electric car becomes more of a lifestyle car, so on cost the Leaf is competing with an Audi A3 or similar.
Kevin Marshall