The benefits of diesel are one of those hidden nuggets in the USA that people just don't know about. They have a really great torque curve for excellent power and return amazing economy, no matter how hard they're driven. My absolute worst tank in my Golf TDI was 39mpg during a blizzard. My best is 49.2mpg. If I drive like a jerk, I get 42-44mpg.
With a 14.5 gallon tank, that's a 700+ mile range. Even when diesel cost more than gas, it was worth it.
This doesn't even touch the longevity of the motor either. I have 325K miles on mine, and that isn't even close to what a lot of people have on theirs. There's people over on tdiclub that have 400K/500K/600K on theirs with minimal problems. Try getting that on a gas motor.
I'm hoping they get the 2016's and up certified, as I'd like to replace mine with another Golf TDI when the time comes.