Noticed a marked drop in mpg recently. For example drove 70 miles today, mostly on M62 with 50mph limits and never over 65mph. Off the motorway I drove very carefully and returned 55mpg for the trip. The same type of trip 6 weeks ago was returning 70+ mpg. Any ideas, or should I just take it to dealers under warranty?

Is it doing a dpf regen or is it due a service, did you change supplier of fuel