A diesel VW (Jetta TDI) will get 40+ MPG and will run for 200K plus miles (w/ a manual transmission) if well maintained.
I had 289,000 miles on my 2001 Jetta TDI and was still going strong, starting every time I turned the key (after the glow-plug light cycled) and was still getting 45+mpg when I screwed up and killed it (truely my fault it died!). The body on all VWs have a 12-year unlimited mileage, transferrable no rust through guarantee. My '01 only had a bit of surface rust in a few corners!
I currently drive a 2012 Jetta TDI and absolutely love it (Tornado red, 6 speed manual transmission). New off the showroom floor, I paid a bit over $22K (OUT THE DOOR) for it with a 6-year, 0.9% finance offer. I couldn't come close to this with a decent used car price/payment combination.
The only weak point in these cars (CR engine) is the new high pressure fuel pump mostly noted in the 2006 through 2010 model years. Unfortunately, the failure mode for this can only be described as "catastrophic". It is something that routine maintenance and checking for signs of imminent failure CANNOT BE OVERLOOKED!
There was a significant redesign of this pump during the 2011 model year. My fingers are crossed that the changes were 100% effective. It was worth the risk for the fuel economy and potential longevity, even if I need to replace the pump (~ $1500) at 100K miles! By that time I'll likely be my own mechanic on this car anyway (I enjoy working on cars!)
As an engineer, I am fascinated by the design elegance of the Subaru boxer engine but had heard word of the head-gasket and other issues with the gasoline versions. There is a Subaru Boxer diesel in europe... ...if this ever comes to the states, I may have to give it a look despite the reported issues with the gasoline versions (...faster burn rate = higher detonation force = higher failure rates!).
Paul E. Turley
"...floats like a Lepidoptera, stings like a Hymenoptera".
David Hyde Pierce in "Fraser" (Season 3, Episode 17).