I am a complete newbie to the world of diesels and I have got lots of questions. Let me see if I can distill this to something meaningful.

First some history: I am currently driving a 1994 Saturn SW2 with 104,000 miles. I bought it new and it's been a great car. It's getting a bit long in the tooth (or at least I believed so until I started looking at this forum), so I'm considering replacing it. I've been looking at new VW TDI 's - either a Golf or a Jetta wagon. I owned a diesel Rabbit pickup in the early eighties and hated it, but the new TDI's seem downright civilized compared to the Rabbit. I like the idea of a diesel, I like the fuel mileage and I like the idea of running biodiesel (there's a B20 pump within 20 miles of my house). However, I live in the Chicago suburbs, have a 5 mile commute each way and put about 12,000 miles on a car each year - not exactly high mileage diesel material.

A new VW will run $18,000 to $22,000 and they are quite small. Works for me, but my 6 year old could use a bit more room. Someone at the TDIclub forum suggested that I look into a used Mercedes diesel. Needless to say, I am fascinated but overwhelmed. So, here's some questions. I'm sure the answers will all be subjective base upon the individual (i.e., me), but I'm going to ask anyway.

1. Should a newbie in my situation even consider a Mercedes diesel? I'm somewhat mechanically minded, but do not like to work on cars (motorcycles, yes - cars, no). I am assuming that I need a good mechanic and that the dealerships are probably not the best place to find one.
2. If so, which models? I keep on seeing ads (on this forum and elsewhere) for diesels from the early to mid eighties with about 200,000 miles on them. I would hesitate to buy something with so many mile, but maybe I'm mistaken...
3. As far as I can tell, ABS is quite available on '85 and later models. When were dual air bag introduced? A car without airbags could be a hard sell to my wife.
4. Should I consider the same budget range as the VW?
5. How available are wagons? I just love wagons - my dad always had one when I was a kid.

Thanks.