They have introduced an array of high-quality, hi- tech models at a wide variety of prices, while the European companies, which historically dominated the sector, have gone into hibernation. Some are finally waking from their slumbers. They have twigged what has happened, and a European sports car renaissance is promised for the next few years.
The role reversal can be traced to the early Eighties. Car companies across the world were about to enter a period of plenty after suffering one of the worst sales recessions on record. Their long-term planners knew the upbeat economic forecasts would translate into unprecedented demand for new cars.
Intriguingly, the Europeans and Japanese fundamentally disagreed over one high-profile market segment: performance cars. They roared off in different directions. Europe took the easier, more direct route that they knew and loved. Japan turned on to the more difficult road.
The Europeans decided consumers would not want sports cars, or even pseudo-sports cars such as the late Ford Capri. By and large, they elected to tune their compact, everyday cars to create the GTi/XR3i/GSi generation of hot hatchbacks.
This approach seemed to make a lot of sense. Makers did not have to bear the cost of retooling for special body styles, and, by adding pounds 100-worth of go-faster equipment and a GTi badge, they were able to charge the customer another pounds 1,000.
True, you can still buy a European sports car, something expensive (Aston Martin, Lamborghini) or esoteric (TVR, Morgan) from a small manufacturer. By definition, anything with a Ferrari, Porsche or Lotus badge is a sports car. The category also includes the VW Corrado, Renault A610, Jaguar's evergreen XJS, certain Mercedes-Benz, and Alfa Romeo's ancient Spider and modern SZ.
Unfortunately for the Europeans, nobody told the big Japanese makers about the anticipated decline in demand for sports cars. The result is today's marketplace, dominated by Toyota, Mazda and Nissan.
While the term 'sports' car is widely used, any definition is open to debate. Generally, people regard a sports car as a low-slung two-seater - or sometimes a 'two-plus-two', where the last two have to be children or pieces of luggage - with a performance edge over more mundane-looking models.
Some cars that masquerade as sports cars are clearly not. A Ford Escort convertible is no sports car: it is a saloon with a soft top. Neither is a Vauxhall Calibra coupe: it may look swish, but the Cavalier saloon heritage is too strong. The BMW M5 and Mercedes-Benz 190-16, despite having performance far superior to that of most sports cars, are still saloons.
The Japanese companies' pre-eminence in the field of real sports cars can be traced to the efficiency of their design, engineering and manufacturing methods. Professor Daniel Jones, co-author of The Machine that Changed the World, coined the term 'lean' to describe the advantage. What it amounts to is an ability to make profits on low-volume production for niche-market models such as sports cars.
European makers, previously imbued with the old gospel of mass production, are now racing towards the new testament of lean production. And while sports models may continue to be a small part of the car business, it is one destined to grow. The Economist Intelligence Unit reports that Britons bought more than 32,000 sports cars last year. That was down from the previous year but not by as much as the market's overall decline. Ian Robertson, EIU editor, predicts British sales of 36,000 this year, and around 50,000 by the late Nineties.
But the appeal to the Japanese of the sports car market goes beyond simple sales numbers. When access to a market is restricted - as it is for Japan in much of Europe - it makes sound business sense to concentrate on more profitable models such as sports cars rather than cheap and cheerful hatchbacks. And sports cars can do a good job improving the image of a manufacturer's entire range.
Many of the new generation of Japanese sports cars are very sophisticated. The technology incorporated in them would shame a racing car of two decades ago: multi-valve engines, turbochargers, anti-lock brakes, multi-link suspensions, electronic controls and widespread use of aluminium alloy in engines, components and bodies.
The variety in Japan's catalogue is second to none. Toyota is Britain's leading sports car retailer with the MR2, Celica and soon-to-be-replaced Supra. Mazda, a much smaller company, has made a speciality of the niche, with its RX-7, MX-6, MX- 5 and MX-3 models. Nissan's flagship is the 300ZX, supported by the smaller 200SX and 100NX.
Honda's innovative CRX and NSX have been admired by even the most ardent Europhiles. So have the Mitsubishi 3000 GT and Subaru SVX, both advanced and luxurious grand touring cars that are being compared to the best of Porsche and Jaguar.
But some of the European companies are planning their response. They will launch several open- top sports cars and coupes over the next few years. Prominent among them will be the two erstwhile leading sports car makers, the Fiat and Rover groups. A Fiat coupe and Alfa Romeo Spider will be unveiled next year. Rover is planning a modern, mid-engined MG for the following year to compete with the MR2 and CRX. Meanwhile, Rover is gingering up interest in the MG name by launching the retro-style RV8 (a modernised MGB) at the Birmingham motor show in October.
Ford is expected to have a roadster about the size and price of an MX5 on the road by 1995. It will be powered by a two-stroke engine, on which the company is doing a lot of development work. Insiders hint that BMW will make another sports car in the American factory it will open in 1995.
The Volkswagen group, too, is known to be keen on sports cars. The next generation Polo (due in 1994) will have a roadster version. VW's Seat division is planning a Toledo-sized coupe. And the recent Spyder and Avus show cars by VW's Audi division are said to be indicative of future models.
The sad part is that the Europeans will merely be attempting to regain what they once had stitched up with marques such as Austin-Healey, Jaguar, MG, Triumph, Alfa Romeo, Fiat and Lancia.