Chris Longhurst’s Carbibles site is a veritable treasure trove of information on everything to do with motor cars. Engines, wheels, brakes, transmissions, you name he covers it, in exhaustive – nay encyclopaedic – depth. It’s a massive undertaking and a daunting read, but there’s gold buried in there, like the The Fuel & Engine Bible, for example, which features a fascinating expose of the many so-called fuel saving devices. Definitely worth a bookmark.
Newer generation diesels start much less noisily but for the most part still have some issues with particulates in the exhaust. Toyota claim to have solved this with their D-Cat and DPNR system. D-Cat stands for Diesel Clean Advanced Technology and DPNR stands for Diesel Particulate NOx Reduction. The operating principle is fairly sound. D-Cat is an advanced computer-controlled system for cleaning diesel exhaust gasses which relies on the DPNR catalyser. This is a combination of particle filters and normal gas-reduction catalysing metals that remove particulates, sulphur dioxide (SO2) and nitrogen dioxide (NO2) from the exhaust gasses.