Fuel-efficient daily commuter, reliable and cheaply maintained. 1000KM/Week!

Take a look at the Mazda 3 or Mazda 6. They are usually cheaper than their Honda counterparts and get better fuel economy.

Supposedly VW's repaired 2015 new cars are now starting to be sold again at dealers, and for extremely low prices. I just did a search and you can buy a "new" 2015 TDI Jetta SEL for under $24k and supposedly the warranties have been extended to cover key emissions/drivetrain parts for 100k. Sounds like it would be perfect for you to keep driving a diesel.

As far as Gas cars, you might consider looking for non-Turbo cars as they tend to be less problematic at higher mileage. Something like a Mazda 3. VW gas powered Golf's get pretty impressive mileage for a non diesel and they would be worth considering.

Chevy makes a diesel Cruz now which could be a worthwile replacement. Interiors are not as nice as VW though. Good luck!

The turbocharged gasoline cuv/small sedans are way to go today. Over 40 mpg at the speed limit and a viable awd that is not offered on some cars make the cuv the better choice.