In the U.S., there's just a single combination of engine and transmission offered for the 2014 Scion iQ. It's a 94-horsepower, 1.3-liter four-cylinder engine paired to a belt-and-pulley continuously variable transmission (CVT). Scion has tuned the car to offer power when needed--by revving the engine--while attempting to minimize the "rubber band" pedal feel and sudden engine surging that make many drivers dislike CVTs.
At 2,100 pounds, the iQ minicar gets around town just fine with this combination. It's responsive, capable, and much more pleasant than the Smart ForTwo in urban and suburban traffic up to speeds of 40 or 45 mph. But beyond that, it starts to run short of breath. Steep hills, highway speeds, even sudden merges that require a burst of speed are all challenges for the little car's little engine.
Part of the problem is that the highest ratio of the CVT actually isn't all that high, which means that at freeway speeds (70 or 75 mph), the engine is howling along at almost 4000 rpm. When you need to pass, you want more revs--but you've already used most of them up, making passing on the highway a heavily preplanned exercise.
Somehow the Scion iQ pulls off the trick of feeling responsive while actually being quite slow: 11.8 seconds from 0 to 60 mph (with much of the time spent in that last 15 mph, we suspect). That's the performance of 1980s econoboxes. The good handling helps a lot; the iQ is as wide as a subcompact, and has large wheels, so it feels firmly planted to the road and drives like a somewhat larger, heavier car.
The brakes are good for all circumstances, despite being discs in front but only drums at the rear, and the electric power steering has been tuned to offer quick maneuverability at lower speeds while reducing wander on highways. And city dwellers will adore the 25.8-foot turning circle, among the smallest of any car on the market. U-turns are possible almost anywhere, with a turning radius only 3 feet longer than the car itself.