I commuted by subway or commuter rail for over ten years, then last November Teradyne closed their Boston buildings and consolidated all east coast operations in North Reading. For the past several months I've been commuting 42 miles one way in our 2003 Honda Odyssey minivan. A good vehicle, but not the most fuel efficient (EPA combined estimate http://www.fueleconomy.gov, 21 mpg; personal mileage, 23 mpg).
I've been looking at diesels, especially with an eye towards biodiesel or converting it to running on vegetable oil.
It's hard to find diesel cars in Massachusetts. The choices seem to be used Mercedes and used VW's. You can find used Mercedes diesels for around $4000, that's not too expensive. The problem is that no matter what you're paying for the car now, the parts are still parts for a luxury car. The rule of thumb for old Mercedes diesels is that you buy them for $4000 and put $4000 per year into maintenance.
On the other hand, TDI VW's less than 10 years old do not seem to be much of a problem with maintenance.
I started searching eBay.
I bid on about six cars (mostly Jettas, a few Beetles), and was either outbid or did not meet the reserve price. On each of them I did my research first, contacting the seller for some details and also researching the VIN's (there are a couple of sites that will tell you about any accident details if you have the Vehicle Identification Number for the car).
One car was local and I really liked it. The car was at Boston Motor Sports. A nice clean little yellow Beetle. (Ailsa says I should name it Esrog, because it's not a lemon.) I looked at the car in person before bidding. On the lot it was listed for $14,000. I bid $10,900 not expecting to get it, but there are always other cars coming up and I wasn't in too much of a hurry. I especially wasn't expecting to get it when my bid did not meet the reserve price.
Backing up a little bit, another very good resource for diesel information I found was TDI Club, http://www.tdiclub.com . They have a very active forum on VW diesel cars. Lots of information available. If you're ever considering buying a used VW diesel I strongly suggest their buyer's checklist of things to look out for http://forums.tdiclub.com/showthread.php?t=75359 .
Joe at Boston Motorsports made me a second chance offer when no one made the reserve price on the auction. I grabbed it at $10,900. (Blue Book Value was $13,900.)
Let me take a moment and say that my car buying at Boston Motorsports, http://www.carad.com/showroom/showroom.cfm?status=200&user_number=9719432 , was the best car buying experience I've ever had. This is my eighth car and I've never liked the hard sell you get at most dealerships, let alone the problems you have getting some things done at dealerships. When I bought my 1992 Ford Ranger at Woody Anderson Ford it took fourteen visits before they did everything they had agreed to do when we first signed the papers.
At Boston Motorsports, I had one problem with the car. The airbag light was on. No problem, they took it to a local mechanic and got it fixed. There was a two day delay because he needed to order parts (seat belt sensor), but there was no problem at the dealership.
I've had the car for just over two weeks now (Ailsa says "When are you going to post about it!?!") and I am very satisfied with it. I'm 6'1" and I am comfortable in it, though anyone in the rear seat behind me will have to be very short. At highway speeds it is much quieter than our minivan. It gets 41 mpg so far.
It's an automatic, so Ailsa is happy. I can drive manual or automatic, but my attempts to teach Ailsa to drive a manual transmission when we had our Subaru Outback were ... interesting.
I had one maintenance problem, there was a water leak. Coming out to a car you've had three days and seeing a pool of water in the passenger footwell is not a happy thing. On the other hand TDI club had the solution (hurray for big forums and Google). The car is now dry and running well and just had it's 70,000 mile maintenance. I've been running on standard diesel so far, but am planning to buy some biodiesel later this week.