The Lexus' whirligig is familiar from the Toyota Camry and Avalon hybrids: a lean-burning Atkinson-cycle, 2.5-liter in-line four-cylinder (156 hp) coupled with two electric motors, one a 141-hp traction motor, the other a starter-generator.

WSJ: 2013 Lexus ES 300h Review: A Smooth, Elegant Guilt-Eraser | Rumble Seat by Dan Neil

Because peak power arrives at different rpm for the gas engine and the electric traction motor, peak system horsepower nets out to be an even 200 hp at 5, 600 rpm, which is the rated redline.

WSJ: 2013 Lexus ES 300h Review: A Smooth, Elegant Guilt-Eraser | Rumble Seat by Dan Neil

The c's program managers were thus obliged to dial back to the previous generation's 1.5-liter engine (the Gen III Prius uses a 1.8-liter), a smaller traction motor (60 hp vs. 80 hp) and a lighter, cheaper nickel-metal hydride battery (19.3 kilowatts vs. 27 kW).

WSJ: 2012 Toyota Prius c Review: Pleasure Not Included | Rumble Seat by Dan Neil