It's actually not quite so bad as that, either.
The original poster assumed 1 barrel of oil->42 gallons gasoline, that is, perfect conversion of crude to gas. This is not the case. Poking around for a few minutes, I found a
link where someone asked what the conversion is, and it's suggested that it's about 20 gallons of gas per barrel of oil, plus other derivatives to make up the balance.
This suggests the amount saved per year is closer to $800 million, which makes the ratio closer to 4:1, or four years ownership of the new vehicle.
Of course, this ignores the various other costs and problems, such as the massive destruction of consumable goods, etc.