As long as you run on Super diesel you're unlikely to promote sooted up EGRs or DPFs, but will eventually have to contend with a worn out EGR, a DPF full of ash and/or problems with the AdBlue heater if the car has an SCR system. You can get 50mpg from a decent petrol engine these days, such as a Peugeot 308 1.2 Puretech 130, so it's whether the additional 10 - 15mpg from a diesel outweighs the potential eventual problems.