>>SNIP
> With Diesel, getting almost double the mileage means the cost of fuel is about half that of gas. In fact, I don't know why diesel engines are not a hack of a lot more prevalent in North America right now.
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>Are you sure that diesel gets twice the mileage?
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>Just because a Jetta can go very far on a TANK, it may be the tank's capacity that is the difference. I don't know.
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>SNIP

It's usually not quite double, but it's pretty close. I had a 55 litre tank in my VW Golf and I got about 900 (just a tad under) km to the tank (city driving mostly). My current Cabrio is gas with a 55 litre tank, and I get about half as much - also mostly city driving. For the record, both are/were standard tranmission. Probably with an automatic, the mileage would be slightly less for the same size tank.