I know you are on the right track buying cheaper gas cars that get less mileage.
Look at it this way. If your car currently gets 30MPG on the highway, and gas costs $3.25 per gallon and you drive 30K per year, you're going to spend $3250.00.
If you get a car that gets 45MPG, and gas costs $3.25 per gallon and you drive 30K per year, you're going to spend $2166.00.
That's a $1084 savings in fuel costs, but only if you stick with a gas car.
If you switch from a 30MPG gasser to a 45MPG diesel, the average price of diesel is over $3.80.
30000/45*3.80=$2533.00
That's only a $717.00 savings per year.
Its not worth the cost to trade up to a more fuel efficient car once you figure the energy savings payback.
And while you'll find a ton of people that say their VW's are great, you will still see the horror stories of folks that lost a timing belt and face a multi-thousand dollar engine rebuild.
Also, no one mentions the $500.00+ service required at 40K, which is on you, as the warranty runs out at 30K.
Buy 3-4 year old Impalas that get 30MPG hwy and drive them into the ground. They are big, roomy, hold 4 sets of golf clubs in the trunk while still seating 5, or even 6 if you find one with a bench seat.