Much of the increase was down to the imagination of the marketing department, however, outputs did approach 400bhp for models like the Chevy Chevelle SS.
It was eventually brought to an end by emissions regulations and the 1973 fuel crisis, and by 1975 the most powerful Mustang could only muster 105bhp.
Today, Europe is looking like America circa 1968. That might seem harsh given how much more fuel-efficient European cars are than American ones, but just look at the figures.
Ten years ago, UK sales of cars with more than 300bhp were less than 4,700 but last year they hit 29,000 (see table). Today, a £28,000 Nissan 350Z produces 300bhp, which is more than a V8 Lamborghini or Ferrari of 20 years ago. A 222bhp Focus ST is more powerful than an early-Eighties Ferrari 308 GTBi.
While it is clear that no-one is going to prise the British motorist out of his car (not least because there is no public-transport alternative for 90% of us), the type of car that is chosen can be changed.
The green lobby has concentrated its ill-considered fire on 4x4s, simply because they are visible: even the dimmest activist can spot the difference between a Corsa and a Range Rover. However, it can only be a matter of time before the green organizations notice the power trip that we are on.
The fact is that power has become very cheap. Modern manufacturing techniques mean that there is virtually no cost penalty in giving an engine a cylinderhead with twin cams and four valves per cylinder – a layout that was just for racing engines 30 years ago.
However, car engines are not like microchips, where increasing power has no side-effects. Even the government must eventually notice that its graduated car tax system is having no effect on our choice of cars – the current top band is 225g/km, so a Lamborghini is taxed no more heavily than a Mondeo V6.
While Mercedes seems to develop a higher performance V8 every year (388bhp is the latest figure for the E500), it should be more concerned with ultra-efficient engines with half that output.
Even well-heeled motorists would rather make do with 200bhp than risk going through the American experience and watch power outputs tumble by three-quarters as part of an environmental backlash.
Sales of cars with more than 300bhp
The number of cars with more than 300 bhp has been growing by 25% a year for the five years up to 2006. At that rate of growth, sales would exceed 100,000 in another five years. Even Volvo now offers four model ranges (S60, V70, S80 and XC90) with 300 bhp or more.