Chevy Volt Faces Its Uphill Battle With "Mountain Mode"

Still can't decide whether to buy the Chevy Volt PHEV when it goes on sale later this year? GM is offering a unique feature to entice customers that are skeptical of the EV's potential performance: Mountain Mode--an option for drivers who know that they are about to climb a big hill.

The Mountain Mode option gathers an energy reserve in the lithium-ion battery so that the car has the full power of both the gasoline engine and the electric powertrain behind it for, say, navigating a series...