All are powered by four-cylinder engines, but the VW is the only one with a turbocharger. It's only a 1.8-litre engine compared with the 2.4-litre Kia and 2.5-litre Toyota and Mazda. Most powerful here is the Optima's Theta II engine with gasoline direct injection. It produces 148kW with the Camry a distant second on 135kW, then Mazda6 (125kW) and Passat 118kW.
Image added: 10 Feb 2012