Expensive. Unruly. Spectacular. Turbocharged engines in Formula 1 are nothing new, but until this season they were banished from the pinnacle of the sport for a quarter of a century.
We have since seen V12, V10 and V8 configurations of normally aspirated propulsion, but now turbos are back - helping to drive F1's new generation of socially responsible, energy-efficient, hybrid V6-engined cars.
Their return has inevitably drawn comparison with that bygone era of flame-belching, tankslapping, 1000bhp-plus qualifying specials. But the drive for efficiency demanded by the latest regulations in F1 means today's turbo engines are very different to their forebears.