The third-generation Audi TT debuted at the 2014 Geneva Motor Show, but so did this TT concept and some might say it stole a significant amount of attention from the production car. The Quattro Sport brandished a highly tuned version of the familiar boosted 2.0-liter four-pot, generating no less than 414 horsepower (309 kilowatts) that naturally went to all four wheels. At the time Audi said it was the embodiment of the car’s potential “in its purest form.” Nevertheless, when the current TT RS debuted a couple years later it carried not this high-strung four-cylinder, but the inline five.