Like any other car, if you take care of the little things, the Passat will be reliable for as long as you wish to drive it. I have nearly 300,000 miles on mine, and other than VW's self destructing heater core, it's never, ever left me stranded. Its fuel economy is okay on the highway (27-30), but what makes this car shine is it's fun-to-drive factor. It's pretty nimble for it's size, and offers very predictable but sporty handling. It has enough room to move a small office, carry a 9 x 12 rug, or a Christmas tree (inside, trunk closed), and offers rear seat passengers enough leg-room to cross their legs withough kicking the driver! this is an all around good, fun, value.
The VR6 engine with manual transmission.
None that matter as this chassis has been retired. My only gripe is the weak window regulators - one tends to go every other year or so.