I have a Jaguar XF 2.7 Diesel and probably do too many short runs for the diesel particulate filter, averaging only 8000 miles a year. So far the light has not come on and I have encountered no problems but as the car is four years old I presume at some point an expensive DPF will be required. However whilst waiting for my car to be MoTd I picked up a leaflet that detailed an alternative of hollowing out the DPF and re-mapping the engine management. On questioning my garage they suggested this was a good idea as it would only be a third of the cost of a new DPF and would increase fuel economy by 2-3mph. Furthermore there would be no MoT implications with exhaust emissions etc. This seems to represent worthwhile savings but what's the catch?