The second big difference is regenerative braking. When you take your foot off the gas – for example, when you're descending a hill or even a modest grade - you feel a slight drag. That's the system collecting the energy from the slowing vehicle and storing it in the battery pack for future use. This too can be off-putting at first. Finally, you have to be wary when you're stopped on a grade because with this system, the auto transmission won't hold the vehicle from rolling backwards. You have to keep your foot on the brake to prevent smacking into the car behind.
But even this modest or hybrid-light system should return 10% - 12% better fuel economy than the regular Sierra V-8.
