I guess any sport which involves an engine and speed, could be called an extreme sport. With that in mind, here are a few which may well rank as a bit more extreme than others.
Land Speed Record:
Do you fancy flashing through a measured mile at over 700 mph? 763.035 mph to be exact, is the current land speed record, and has been since 1997. If you fancy the ultimate adrenalin rush, have a spare rocket engine lying about, and a few million pound to invest, what better way?
Still talking big engines of all types, a chassis, a seat, and little else, drag racing competitions are usually run over a measured quarter-mile. Two vehicles at a time, either motorcycles or cars, are raced down the track to see who crosses the line first. The speeds reached in such a short distance are quite phenomenal.
With a large variety of different categories of vehicle and engine types and sizes, and a worldwide following, drag racing is well established as one of the favourites of extreme motor sport.
The Dakar Rally is probably the most famous of the off-road rallies. A rally open to motorcycles, cars, lorries, and heavy goods tractor units, it originally began in 1978 from Paris, as the Paris-Dakar rally. Since 2009 it has been run in South America, and the name changed to the Dakar Rally.
Another desert rally, the Bajo 1000 may be better known in the US.
This wholly American phenomenon, involves driving high powered saloon stock cars, around an oval track at speeds of 200+ mph. A definite spectator sport the crashes are many, and often include burning high octane fuel spewing across the track from ruptured fuel tanks.
The Isle of Man TT:
Extreme motor sport for the two wheeled enthusiast, the Isle of Man TT is run over the last week in May for practise, and the first week in June for racing. Started back in 1911, it has gone through various formats over the years but has always included racing on public roads.
Considered by many riders to be the most dangerous road race in the world, it is more a time trial than full race. Each rider starts alone, and is timed over the 37.73 mile course. The meet ends on the second Friday, with the prestigious Senior TT race.