As long as the current differential between petrol and diesel exists which is about 20%, the higher cost of diesel negates the increased mileage of the TDI. As a former mechanic, I would suggest you call the nearest VW service manager and ask what the cost of changing the timing belt on the OHC VW Beetle diesel which does need replacement every 100K or so. It is close to $1000. I do hope that we can get away from these attempts to prolong a POV transportation lifestyle and talk about a transport modality with a future and that will be electrified rail. We probably have 3 or 4 more years of relatively cheap oil until the supply demand curve really crashes and we need to start crushing our beloved Hummers and Excursions now to recycle the steel and start laying track ASAP!

Jon

The Prius is realy optimised for city driving, It does have an Atkinson cycle engine which improves its cruising economy, The VW has the advantage of a more efficient diesel (due to the higher comp ratio) and the higher energy content of diesel. But for your application the VW is a better bet.

HTH

Neven

The advantage of the Prius is in city driving, where it's battery pack actually allows it to get higher mileage in the city than on the highway. That's the opposite from a standard ICE auto.

This graph is somewhat artificial in that people don't drive a constant speed from place to place.

That graph doesn't reflect my Prius experience at all. In good conditions, I usually get 55 to 60 mpg at 55 to 60 mph. (Though I live in Colorado, where the air is thinner and dryer than in most places, and really does make a difference at higher speeds.) In three-plus years I've had only a handful of highway trips under 50 mpg, and all of those involved either cold - low 20s or below - or freezing wind. In the Prius, cold wind and short trips (in minutes) are the real mpg killers.