Emissions Testing Lab recently tested the effects of a Webasto coolant heater on the emissions performance of a diesel engine.
To simulate different temperature conditions during the seasonal changes and the effect caused by the Webasto heater, boundary conditions to the test engine were set at 40 degrees F and 75 degrees F during separate test runs.
Cars doing local runs are just not getting hot enough or running long enough for the regeneration to start.
You may or may not be aware that Diesel cars now have fitted an item called a DPF (Diesel Particulate Filter). What this does is help to clean up diesel emissions, and they do it very well as most modern diesel cars have almost zero emissions. In fact MOT stations had to upgrade their Emissions Testing equipment because of this.
