Gentlemen's handshake

In 1989, Japanese carmakers entered into an informal agreement, known as the "Gentleman's handshake" where each agreed to limit the advertised power output of their vehicles to 205 kW. According to Car and Driver, this was to avoid a "horsepower war" in Japan, where speeds are limited to a maximum of 100 km/h.

The agreement lasted until 2005 when Honda released the Legend with a 223 kW 3.5 litre V6.

Despite there being an agreement to advertise vehicles as having no more than 205 kW, it has long been known that the Mitsubishi Lancer Evolution, Subaru Impreza WRX and Nissan 300ZX twin turbo produced more than the advertised power. Carmakers have deliberately advertised their vehicles as having less power than they produced so they could keep the agreement.

References

http://www.caranddriver.com/news/car/05q1/japan_dumps_276-hp_pact-car_news