The purpose of a DPF is to remove any build-ups of soot and ash as you drive. However, over-time they can become clogged minimising the purpose of the filter. If you own a diesel car, then it is highly likely that it will have a DPF. Soot and ash are two different things in this circumstance. A lot of DPF cleaners will only clean out the soot, and not the ash. However, the new Quantum DPF vehicle cleaning system cleans soot and ash and is chemically pressurized clean not heat cleaned.