Diesel-powered cars are gaining in popularity and it is easy to see why: fuel seems to get more expensive all the time and diesels generally use less than an equivalent petrol-powered vehicle. You can go further on a tank of fuel, in other words.
Diesel engines are also much better than they once were. No, they still don't have the outright power and ability to rev hard like a petrol engine but the application of some very specific technology means performance is better and noise levels are generally lower.
Those tell-tale plumes of black smoke from diesel exhaust pipes are also on the way out. Not only is black smoke smelly and unsightly, it's also bad for you. It consists of very fine particles of soot created when diesel fuel combusts and is a known carcinogen. Think of it as an almost gaseous form of those carbonised sausages off the barbecue.
The trick for car makers is to remove the smoke and the best way of doing that is with a particulate filter. The very simplest form of filter (used in industrial applications) is made of paper and has to be replaced when it gets clogged with soot - and that's hardly a viable proposition for most car owners.
So the best ones use a catalyst in a metal container joined to a car's exhaust pipe, which contains (usually) a silicon carbide filter that collects the soot.
The really good ones collect more than 99 per cent of the dirty stuff.
The clever bit, though, is how all the gunk gets cleaned out in a process called filter regeneration. Peugeot, for instance, uses what it calls an FAP (that would be a filtre a particules) with sensors that tell the engine it's time to burn off excess soot.
An additive from a reservoir squirts into the fuel injectors and the exhaust temperature rockets to 500 degrees or above and the soot is oxidised. When your Peugeot gets serviced, the additive reservoir is refilled.
The bad news is that high sulphur levels in diesel fuel can interfere with filter regeneration. Australian diesel falls into that category, so particle filters aren't common in cars or four-wheel-drives sold here. If you're interested, check before buying a diesel.
Last week's column should have said the "R" on a tyre's side stood for "radial".
Read more at drive.com.au/motoring-101