The 2013 Scion iQ's small size seems to inspire onlookers to guess at astounding levels of fuel economy: 60 mpg? 70 mpg? But cars like the iQ still have to push the same amount of frontal area through the wind at high speed, despite their lighter weight. So while they're more economical than most cars that are larger and more powerful, the gains are surprisingly small--and don't bring the Scion iQ up to the level of any Toyota Prius hybrid, for example.
With an EPA combined rating of 37 mpg, the littlest Scion marginally better than the aging Smart ForTwo, at 36 mpg. But with a city rating of 36 mpg, the highway rating--which most seem to peg at well above 40 mpg--is just 37 mpg. The ForTwo, by comparison, is rated at 41 mpg highway.
Part of the blame goes to the highest ratio of the CVT, which is actually lower than expected. That means that during brisk highway driving--70 or 75 mph, say--the engine is spinning up toward 4,000 rpm. Over several scenarios of hard stop-and-go and enthusiastic highway driving (pretty much worst-case-scenario) during a first-drive opportunity, we saw figures in the upper 20s.
Still, on an absolute scale, 37 mpg is better than almost any other non-hybrid gasoline car, and we rate the Scion iQ as a more pleasant way than the Smart ForTwo to achieve that mileage in a very small vehicle.