It's been one year, almost to the day, that I came home with a 2012 Volkswagen Golf TDI, having left a 2001 VW Golf at the dealer. The transaction nearly doubled the fuel efficiency of our family car.
The mileage meter says 8300 miles. That's a little higher than our average annual mileage over the past ten years, about 8000 miles, but well within the year-to-year variation.
So it appears the old adage about higher fuel efficiency being futile as it leads to higher annual miles doesn't apply to us. I never did believe that tale, anyway. In my particular case, I would have to start driving 15,000 miles per year instead of 8,000: where would I find the time to put on those extra miles?
The car has been averaging 38 mpg. On the one road trip we've taken with it, it got 45 mph on the highway. Since it was carrying all four of us (but not the cello), its per-passenger carbon emissions rivaled that of a European high speed train (Amtrak needs to do some catching up in that respect).
I've had no trouble getting diesel fuel: when traveling, it's not hard to find fuel stations dispensing diesel - and with a 500-mile range, it's easy to plan ahead a little. Around town, there are one or two stations where I've become a familiar customer.
In the normal course of things, I visit that fuel station just about once a month. I like it that way.