Modern diesel engined cars have dual mass flywheels, diesel particulate filters, exhaust gas recirculation valves, turbos and many of them are also belt cam. All components that may fail or may need expensive routine replacement. While, in the past, the lubricity of diesel actually made diesel better for repeated short runs from cold, a diesel particulate filter will not tolerate this. But the type of use you describe should be fine to allow the DPF to regenerate properly. Just avoid repeated short runs from cold in which the engine never fully gets to temperature. They will fill the DPF with soot, which it cannot get hot enough to burn off. For DPF flushing liquids, try www.powergo.co.uk