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!