Hi Vinny,

It's more about the type of mileage than the duration of it, and there are no hard and fast rules as every engine and every exhaust system and every DPF is different. Put simply, though, the DPFs need a regular run at elevated temperature for more than just a few minutes. If a car is being used on the motorway a lot anyway, and that motorway isn't gridlock all the time, then it's probably fine. If not, then it should be taken out on a weekly basis and driven for at least 15 minutes with the engine revs higher than normal (i.e. use a lower gear on the motorway, so you don't have to speed). There really are no hard and fast rules on this, however. We reckon that more 1.6-litre diesel engines should be doing over 20,000km a year, with a good deal of that on the motorway.