Concerned that drivers will suffer performance on the steepest of grades, General Motors engineers have included a "Mountain" mode in the Chevy Volt to boost the available power.
Mountain mode, which will be selected by the driver, is essentially a cue to the car to start storing up extra energy in the battery. Once in place, it means that the car will have all the available power from the gasoline engine and batteries, explained Larry Nitz, GM's executive director of hybrid and electric powertrain engineering, during an update with the media on Tuesday.
There are few circumstances where Mountain mode will be actually required, if any, Nitz said. People will still be able to climb mountains, but they can expect a drop in performance once the car's power source switches over to the 1.6 liter gasoline engine for the biggest mountain ranges in the country, he said.
The car is designed to drive about 40 miles on the energy stored in its batteries and then tap a gasoline engine, which generates charge for the batteries. The engine can deliver 55 kilowatts of power, which is about half of the total available power when the car is fully charged, he said.
"There are a few grades in this country where the vehicle performance needs to be higher than 55 kilowatts, so we wanted to offer this feature. Not that you won't be able to go up the grade. It will slow down a bit," he said.
If drivers plan ahead, they can turn on the Mountain mode and create a deeper reservoir of charge in the battery, which will provide more power than is available from the batteries in the normal mode, he explained.
The Mountain mode feature is one of many that GM is adding to the Chevy Volt, due to go on sale later this year, to address changes drivers may experience in going to electric. There will also be a Sport mode, which will make the accelerator more responsive.
Overall, the mileage or range of electric vehicles will vary significantly in all types of battery-powered cars, depending on the outside temperature, the terrain, and the driving technique, Nitz said. Nitz and GM engineers are currently fine tuning the Volt by testing it in various driving conditions, including stop-and-go traffic and mountain driving, in California.
He declined to provide specifics on how much range will vary but said all cars that rely on battery power face the same issues. BMW gathered data over the past year for the 600 all-electric Mini-Es it had leased and found that range varied from about 75 miles to 100 miles depending on weather conditions and driving styles, company executives have said.
To put it in perspective, Nitz said that heating the car and passengers on a "cold Midwest morning" requires more energy than to actually move the car. "That's just the physics of it." He argued that GM's Chevy Volt design, where the first 40 miles are all electric and then a gas engine kicks in for longer trips, means fewer compromises than an all-electric approach.