In slightly less than a month, at the 2014 Washington Auto Show, Green Car Journal will announce this year’s winner of the 2014 Green Car Technology of the Year Award.
We’ve been considering the ten nominees, one by one, such as BMW’s CFRP body, Audi’s new TDI engine, and Acura’s SH-AWD powertrain. Today’s green car technology pick is the Cadillac ELR’s Regen-On-Demand system.
The Cadillac ELR is green car technology in a luxury package, that is, it uses an extended-range electric vehicle (EREV) powertrain, which is based roughly on the powertrain used in the Chevy Volt. A lithium-ion battery pack powers the electric motors and, when the battery pack runs out of juice, a gasoline-powered electric generator provides the energy to keep going. The electric motors and battery have been tuned to deliver more power, befitting the luxury vehicle the Cadillac ELR, which will probably cut down a little on electric-only range.
Like most hybrid and electric vehicles, the Cadillac ELR employs regenerative braking. When the driver steps on the brakes in these green cars, the hydraulic brakes don’t actually function unless he is making a panic stop or if the car is going less than 20mph, more or less. Instead, regenerative braking slows the vehicle by turning the electric motors into generators. The resistance in the electric motors slows the vehicle and feeds electricity back into the battery pack. Letting off the accelerator, the car’s regenerative-braking logic approximates the feeling of a conventional vehicle idling at highway speed, slowing down gradually, but not coasting.
In the Toyota Prius, a hybrid electric vehicle, the “B” position of the gear shift accentuates the regenerative braking when you release the accelerator. The Cadillac ELR goes one better and puts regenerative braking at the driver’s fingertips. Cadillac ELR’s Regen-On-Demand functions kind of like paddle shifters on a sequential-shift automatic transmission. Instead of shifting, however, Regen-On-Demand green car technology approximates the feeling of downshifting, decelerating the vehicle and pouring energy back into the battery.
Image © General Motors