Hello Doc,

I think that you have perhaps covered this before in these pages, although maybe not for a while, as I could find no reference to it in recent issues. What would you consider borderline conditions, in terms of freedom from particulate filter problems (DPF), in terms of the length of typical journeys and frequency of longer journeys in excess of around 20 miles or so?

We’ve had a Clio 1.5 dCi for three years now, and it has been totally problem-free and economical, but with retirement now looming, I’m not going to be doing my daily commute of 18 miles each way. Is this going to compromise reliability and freedom from DPF problems? In spite of the end of the daily trips to work and back though, we still expect to visit our nearest big shopping city of Cambridge once or twice a month, which will be 22 miles each way to the Park & Ride that we’ll use, to avoid the awful traffic and costly parking (not that the Park & Ride is cheap!) and adding to and breathing in, the nitrogen oxygen laden city air pollution.

By the way, is the 1.5 (1,461cc) engine used in the Mercedes-Benz A- and B-Class really the same engine as in our Clio? It is a fine engine, and very economical, but it seems to have been around for a good few years now. I’m not sure I would expect to find a Renault engine under the bonnet if I was spending £25,000 plus on a Mercedes-Benz! Your advice would be appreciated. 

Regards, Bernard Flood, Chatteris

I think that I can confidently reassure you on this Bernard. I’m reasonably familiar with your part of the country, and I am sure that a trip down the open roads to Cambridge will give your Clio enough opportunity to burn off some soot when it’s necessary, as long as you do that type of run or something similar every couple of weeks or so. I think one of your alternative routes could be via the A14, coming into Cambridge from the north west, and that would certainly give you the opportunity to let the Clio stretch its legs, as long as you avoid the morning and afternoon rush hours! The engine will certainly get warm enough to do what is necessary, but Renaults, and this engine in particular, have always been good at regenerating the DPF at fairly low temperatures, and the filter unit is located close to the exhaust manifold, which helps a lot.

Yes, it is the same engine that has been used in the A- and B-Class, subject to some Mercedes-Benz modifications, which is a pretty good recommendation for it. I had a long-term loan of a Modus a good few years back, and the 1.5 dCi engine delivered great performance and economy back then, with only 80bhp, since when it has been tweaked up to 114bhp, which is quite a lot for a 1.5-litre engine.

Hope this helps.

Best regards,
Doc Diesel