Electric-car aficionados have been eagerly awaiting big breakthroughs in the second-generation Chevrolet Volt, and they won’t be disappointed. But the advances may not be the ones fuel-economy enthusiasts were looking for.

Sure, the 2016 Volt has a little more range than the outgoing model—GM claims a 20-percent bump, from 40 miles to 50 miles. We got 35 miles from the Volt we tested, so figure the new one may achieve around 40 real-world miles on electricity.

It also gets more energy-generation power, with the engine output climbing from 84 hp to 101 hp. Displacement also grew incrementally, from 1.4 to 1.5 liters. The electric drive remains at 149 hp. Shaving about 250 lbs. off the curb weight should help both performance and efficiency. Plus, the gas engine no longer requires premium fuel.

But none of those are the biggest breakthroughs. In our own testing, the Volt mostly performed impressively, with silent, smooth electric power and acceleration better than a Toyota Prius. Where it fell down was in the everyday details that made it hard to live with: the jumble of indecipherable and unresponsive capacitive touch buttons, the rear seat cramped into near uselessness, and the total lack of a center rear seat where you could install a child seat.