Any tips on what to look for and/or avoid on BMW or VW diesels? I drive my F250 everywhere when I'm not on the clock and a smaller, quicker, better mpg car would be appreciated!
The 2.0 liter VW diesels are quick enough to not be boring and have no problem getting out of their own way, but are not exciting from a power standpoint. My 2004 Passat TDI was actually faster and zippy-er than my 2014 Passat TDI. Both rode and drove and handled great, had huge trunks, comfortably carried 4 adults, and easily knocked down over 40mpg highway, and 35-40mpg around town.
The BMW 335d was darn quick when stock, stupid fast when deleted and tuned, but had a smaller backseat and smaller trunk. It was sportier in every way, handled amazing, had great brakes, but also rode stiffer and went through rear tires rather quickly (partly my right foot, and partly because of the 2 degree camber spec in the rear). It regularly achieved 30-32mpg average, and could get in the upper 30s on the highway. You can find them in the sub $10k range with higher miles. I'd try to find one that is already tuned and deleted, as that is an expensive proposition on these cars.
If you're looking for economy, I'd look for a 2011-2015 Passat. Bonus points for a 2015 because they are hard to find and have a next generation engine (diesel gate killed off all future TDIs). You could also get a Jetta if you want a wagon, or a Golf if you want a hatchback. But the Passat is the biggest/nicest/most powerful, and economy is about the same for all 3. The Passat was available in SE or SEL. The SE could be had with a 6spd manual, or 6spd DSG. Mine was a DSG and was pretty good for an auto. The SE comes standard with "leather", heated seats, Bluetooth, backup cam, cruise control, power everything, etc. The SEL is auto trans only, and the only real upgrades are foglights, better leather, navigation, and remote start. All are front wheel drive only. They are pretty good cars and not too difficult or expensive to work on.
If you want to go down the BMW rabbit hole, they are only available in rear wheel drive automatic trans. The main packages are the cold weather package (heated steering wheel, turned me into a puss but I loved it), sport package (useless paddle shifters on steering wheel, nice looking 18" wheels, and the most comfortable seats of any car I've ever owned), and navigation system. This car has the dumbest cupholders ever and nowhere to put your phone. Otherwise the ergonomics are good and the driving experience is great. They are easy enough to work on and actually pretty reliable, especially when tuned and deleted. They were only available in the US from 2009-2011. Very little difference between the 3 years. Mostly just color options, and the 09 and 10 models had aluminum shifter paddles that allowed up or downshifts from either hand, whereas the 2011s are plastic and have downshift only on left and upshift only on right. But the position is poor and I found 98% of the time I just used the shift lever in manual mode anyway, so if i were to ever buy one again, that feature wouldn't matter. But the sport package is worth it for the seat adjustability. Bottom line on the 335d is that rolling coal in a dual exhaust "luxury car" puts a smile on your face every time!