So, it takes energy out of the wind induced by driving cars. I think that must mean that it slows down that wind, decreasing the benefit other cars have drivin

So, it takes energy out of the wind induced by driving cars. I think that must mean that it slows down that wind, decreasing the benefit other cars have driving in the wake of other cars. I think the net effect will still be positive (especially on roads with traffic in two directions close to each other), but still, the energy has to come from somewhere, and I don’t think _all_ of it comes from wind that wouldn’t help other cars driving along the same path. So, what’s the effect on energy usage of the cars?