Kia Carens - Diesel - Value for Money

I have been using Kia Carens Diesel top of the line model. Average in the city depends but still I get 10-12 but when I travel frequently to Pune , I get 22 - 27. But recently after 15 months of purchasing and driven around 8900 kms I got an alert of Diesel fuel filter regeneration. I drove at a speed of 65 km/h for around 20 mins and the alert went off & next day car was picked up by the dealer for necessary action.