Accelerating your car uses fuel. Decelerating the car turns that energy that you just burnt in gasoline into heat from the brakes. Wasted energy. If you assume that the average gasoline engine is 20% thermally efficient (meaning that 20% of the energy in the gasoline actually goes towards propelling the car the rest is all wasted heat dissapated into the atomosphere via the radiator) you begin to understand how completely inefficient cars actually are. Toyota is almost to 50% in current production hybrids, but the modern internal combustion engine is still not that efficient.

Have you ever had your cruise control set at the speed limit and then been passed by some idiot, you get to the next stop light and he’s right there beside you? He’s the problem. Slow down. Accelerate slowly think about conserving momentum and not accelerating so fast if you are just going to stop again soon. It’s totally stupid and pointless to accelerate quickly.