We talk to Robert Pepper about the future of Diesel engines in 4 wheel drives.  My last 3 4WDs have had diesel engines and I have loved the economy and reliability of diesels. Vehicle emissions have become increasingly under the microscope as people become more aware of the effects on the environment.  Whilst the fuel economy of diesel has been great (my old Patriot was getting 6.5 liters / 100km) the emissions are a lot dirtier. The United States has never really embraced diesels, nor has the Middle East, but diesels are very popular in Europe. We talk about the Common Rail Diesel design, and how that works. We look at some of the ways that engine designers have tried to make diesel engines more environmentally friendly. Exhaust Gas Recirculation, whereby some of the exhaust gas and how it works to decrease Nitrogen Oxide emissions. Diesel Particulate Filters and how they work. AdBlue, one type of Selective Catalytics Reduction.  We look at how this works, and more importantly, what happens if you run out of Ad Blue when you are out bush. We talk about Dieselgate, where VW and a number of other vehicle manufacturers built software to decrease performance What will the introduction of Euro 6 mean for Australian vehicles?  New cars sold in Australia after July 2018 will have to meet Euro 6 and the Ford Explorer already has AdBlue fitted. There have been a lot of developments with petrol engines, although petrol is probably on the way out as well. In the UK, they are banning the sale of new petrol cars in 2040 and Volvo will drop Petrol and Diesel cars after 2019, so the writing is on the wall. This is a sad development for fans of the big oiler engines, it will be interesting to see what an electric 4 wheel drive will be like off road.