A dramatic demonstration of this is the Bugatti Veyron. Between the original version (1,001 hp) and the SuperSport version (1,184 hp) - the top speed only incr

A dramatic demonstration of this is the Bugatti Veyron. Between the original version (1,001 hp) and the SuperSport version (1,184 hp) - the top speed only increased from 408 kmh to 431 kmh. So a 183 hp increase in power yields only a 23 kmh increase in top speed - bearing in mind that 183 hp is more than most passenger vehicles have in total. It gets exponentially harder to push air out of the way the higher the speed gets.