How do I keep the diesel exhaust filter (DPF) healthy?

Dear John,

I am seeking your advice. I currently drive a 2000 Mercedes-Benz C200 Kompressor Elegance W203. Whilst I like this car, it is now far too low for me and my wife as we have difficulty getting in and out and are looking at upgrading to a modern SUV with easier entry and exit. I drive about 10,000 kilometres every year.

Kia Sportage Platinum has a potent 2.0-litre direct injection turbocharged diesel, slick six-speed auto and on-demand AWD

Kia Sportage Platinum has a potent 2.0-litre direct injection turbocharged diesel, slick six-speed auto and on-demand AWD

At this stage, I am favouring the Kia Sportage 2.0 litre diesel AWD because of the seven-year warranty and its feeling of power. However, I am getting conflicting reports on the need to regularly drive some distance to clear the exhaust filter system. Some say this was once necessary on older diesels but the modern diesels are more or less self cleaning. The local service centre for Kia cars told me that they don't have any problems with Kia diesels as far as the filters are concerned. I would use the car mainly for local running with occasional longer trips (say 25-100km) and touring.

The 2.0-litre petrol engines in the Tucson and the Sportage seem to be revving high to achieve any performance. 

Could you please advise on the exhaust filter requirements of a modern diesel motor.

Thanks in anticipation.

Hyundai Tucson

Hyundai Tucson

Hello John,

In relation to the points you raised:

  1. Kia Sportage >> will be easier to get in and out of - hip height seated will be close to your standing hip height, minimising the 'climb up/down' demands.
  2. The diesel powertrains of the Hyundai and the Kia are identical. Performance is therefore identical. (Hyundai and Kia are different brands owned by the same parent company. They share fundamental engineering to constrain R&D costs. Styling and minor specs/tuning are the only differences between competing models in the Hyundai/Kia ranges. (Hyundai has a 1.6 turbo petrol and dual-clutch transmission as its premium petrol offering in Tucson, and Kia went with the 2.4-litre atmo engine and conventional auto with Sportage...) If you look carefully you’ll see both vehicles have the same major body panels. Hyundai Tucson >> diesel has the same engine, transmission and on-demand AWD system as Sportage.)
  3. Modern diesels with particle filters need occasional runs for 15 minutes or more at 60km/h+ to regenerate the particle filter. In total about one hour a month is all that’s required. That's a ballpark figure. This is not an onerous operational demand - go for a coffee once a week to once a fortnight with your wife somewhere reasonably close with a view… That will be more than enough.
  4. If you don’t do sufficient touring to regenerate the filter, a warning light pops up. If that occurs you can either head immediately for the highway and go for a drive, or head to a dealership and they can manually regenerate the filter in the service bay. It’s not really a major deal.
  5. You’re used to driving a supercharged engine. Naturally aspirated petrol engines need to rev to about 6000rpm to make maximum power. That’s just how internal combustion works. Supercharging lowers the peak power revs and increases low-rpm power delivery. Turbocharged diesels with direct injection (ie all modern diesels) make 2-3 times more mid-low rpm power than their petrol counterparts - thus making the petrol equivalent feel somewhat underpowered at lower revs. The C200 Kompressor you've been driving has the badge everyone lusts after, but is hardly a world-beater - you'll be impressed with the Sportage/Tucson. Mercedes-Benz Myths >>

See also Should I Buy Petrol or Diesel? >>

John Cadogan