On the highway, the iQ doesn't nearly approach expectations. The iQ's EPA city rating is an excellent 36 mpg, but its highway rating is a hybrid-like 1 mpg higher, at 37 mpg. On the highway, that's a few mpg behind much larger sedans like the Hyundai Elantra and the likes of the Chevrolet Cruze Eco and Ford Focus SFE.
At root of the issue is likely that a rather low top-gear ratio for the CVT has the little four spinning up near the 4,000-rpm range in brisk highway driving. 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.
All this said, the 2012 iQ is arguably a little more fuel-efficient overall than the other mini that it compares most readily to, the Smart Fortwo. With its 37-mpg Combined figure, it beats the Fortwo by 1 mpg—although the Fortwo's 41-mpg highway figure is quite a bit better.