3 ms·

Does this apply to cars? I always wonder if there's a mileage bonus for riding with a half empty tank.

• ac29 5y ago
  Sure, it takes less fuel to move a car that moves less, but fuel is an nearly irrelevant fraction of total weight in most cars. A gallon of petrol weighs about 6 lbs.
  • fragmede 5y ago
    But what's the math on mpg difference for moving an extra 60 lbs? It's probably pretty negligible but without actual numbers, can't actually say.
  • tehjoker 5y ago
    Thanks, I wasn't sure how heavy the gas was. So it's like carrying an extra child in the car.
• gruez 5y ago
  A heavy car takes more energy to get up to speed. The extra weight also "stores" more energy once you get up to speed, but that's useless when you don't have regenerative braking. Also I'd imagine that rolling resistance would be higher when the car is heavier.
• deleted 5y ago
  [deleted]
• roelschroeven 5y ago
  As gruez says, a heavier car needs more fuel to accelerate and has more rolling resistance. It also needs more fuel to drive up a slope. Some of these can be regained in a car with regenerative braking, but even than only partially because there are always losses. But the difference is not nearly as large as it is for airplanes. Having your fuel tank only half full means more trips to the gas station, which might even negate all gains you try to make. It seems a good idea though not to drive around with things live heavy tools all the time when you don't need them.
• olliej 5y ago
  For general cars it’s negligible, but for formula 1 it matters: I think it’s in the order of 1/10th a second per lap or something - the car get multiple seconds per lap faster over the course of a race (despite the lower grip as tires wear)