The 2011 Chevrolet Volt extended-range electric car will offer a capability that General Motors hasn't previously discussed: a "Mountain Mode" that the driver can select if he knows that he will be climbing a long hill.
GM's executive director of powertrain engineering Larry Nitz revealed the new feature on a conference call today with the 2011 Volt development team.
The team is currently testing a fleet of 10 Volts throughout California, with a route including hilly San Francisco urban traffic, the long eastern climb up Interstate-10 to Tahoe, a run through desert heat to Las Vegas, Nevada, and then back down into the Los Angeles basin and its notorious traffic.
Mountain Mode builds up an extra energy reserve in the lithium-ion battery when the Volt operates with the internal combustion engine generating power to drive the front wheels.
The Volt's naturally aspirated 1.4-liter engine generates 74 horsepower (55 kilowatts), but its electric drive motor can operate at peak output of 100 kilowatts. To make up the difference, the car will pull power from the battery pack under very heavy loads.
If the driver knows the car will be operating under heavy load for many miles--climbing thousands of feet at high speed, say--Mountain Mode not only draws more energy than normal from the pack, but runs the engine at higher speeds to maximize its output.
Nitz admitted that under a "limited set of circumstances," on a handful of known grades in the country, vehicle performance "may be degraded" under sustained heavy loads when the engine providing electric power to drive the car.
The Mountain Mode option helps compensate for this in some circumstances. While drivers may not be used to planning ahead, future navigation systems might suggest that the special mode be triggered if it knew that a preset route included a long uphill stretch.
Nitz declined to specify the impact of Mountain Mode on overall range or effective fuel economy with the engine running.
The first 2011 Chevrolet Volt models will reach dealers this October, one month earlier than expected.