The problem with many modern diesel engines is the Diesel Particulate Filter, which are designed to gather unburned hydrocarbon soot on start up, then burn it off in an environmentally friendly way later in a car's journey. This makes diesel engines with DPFs unsuitable for repeated short runs from cold starts because there is no "later" so the soot does not get burned off and eventually chokes the DPF.

Some manufacturers (Renault, Mazda, BMW) counter this with technology that heats the DPF extra quickly. Some use Eolys fluid to help the DPF regenerate (PSA/Ford/Jaguar). Many use systems that inject extra diesel fuel into the engine to regenerate the DPF but this does not always work and the extra fuel can sink to the sump, contaminating the sump oil and even raising it to a level where the engine can run uncontrollably on its sump oil. It is therefore vital for all users of diesel-engined vehicles with DPFs to keep their DPFs clear either by buying vehicles with fast warm DPFs, by running the vehicles longer distances, or by using DPF cleaning additives.