What does the manual say about intervals? A quick online search tells me that VW of this era should have an oil change every 5000 miles if you use petrolium based oil or 10K for synthetic - so - assuming synthetic oil - every 3 months would be good. But, check your car manual - I have no way to tell if the internet data is accurate. Check the timing belt thing, however. The same internet check tells me that VW uses a timing belt, not a chain, and that as I remembered - it is an interference engine.
I do not think depreciation, finance charges and travel time costs really figure in his calculations.
Depreciation certainly matters. How many miles on his tires? Those need to be replaced. Will his engine need to be rebuilt at some point - that cost has to be accounted for.
The car could last forever (well, a really long time), as long as the frame isn't bent and it doesn't rust to pieces. You can replace just about every part on it as need be. I happen to like VW. I owned a 1973 Bus and a 1984 Vanagon and they were very reliable. That 1973 bus probably had 450K miles on it - it was over 25 years old when I donated it to charity. It also held up its resale value - I paid $2500 for it and that's about what it cost new. I see a LOT of old buses on the streets here in San Diego.
He paid $6500 for it. The 27c/mile figure in that link is just not relevant in this case. This car had most of it's depreciation happen already. A new Jetta is a $20K+ car - so for the next 5 years or so the car is going to depreciate an extra $3-4K at most - in other words - it is not really relevant to his calculation.
Or any of the indirect costs, which are communal costs for vehicle miles, not something the individual pays. The fixed costs are exactly that, fixed. Your cost per mile goes down for your insurance, registration, etc. the more you drive. In fact, if you never drive your car, your cost per mile is infinite for those costs. Travel time? Accidents? Residential Parking? Man, this thing must be a propaganda piece for those who want to push public transit.
Enjoy Montreal. It's a wonderful city. New Haven, not so much. You'll be highway driving most of the time (I think I'd head through Albany and take I-87 all the way up). Since you'll be looking for the little things on your drive, check a sign on Northbound I-87 that has arrows pointing in different directions. It seriously says, "Canada" with one arrow and "Mexico" with another. Of course, it's Mexico, NY, but that sign always humored me.
Your cost per mile on a cash flow basis goes up when you buy new tires, have engine work done, have new brakes put on, etc. The more you drive a car, the more often those costs come into play. Buying a car with 85,000 miles already on it, a few of these things may be due sooner than later. If he bought his car for $6500 and sells it two years later for $2500, you can take that $4K loss and divide it by the # of miles he drove and that's a per mile cost, too.
I agree with Thrilla. I think you'll make the drive once or twice then just drift apart and not want to anymore. Watch "Road Trip".
I will offer a bit of warning about driving in the snow belt. Wash your car frequently if you want your car to last. NY is especially bad when it comes to salting the roads. Upstate, the car body and chassis will fall apart from rust before they fail mechanically. Also, if you're parking on the street in Montreal, be alert for snow emergencies. The tow trucks follow the plows and tow at the drop of a hat. And if you have US plates? Fugedaboudit.