The majority of energy expenditure is not acceleration and deceleration (especially on an EV with regen braking). At moderate and high speeds wind resistance dominates. At slower speeds rolling resistance is a largish factor.

And what does Newton say about regenerative braking? Does the energy you put into the system just go puff?

I hate when people make smart-ass claims with surface level knowledge at best.

> Does the energy you put into the system just go puff?

Yes, actually. The most common example of this is drivetrain power loss, which EVs are not immune to. Tesla engineers have stated that they are ~15% which is about the same as with ICE vehicles.

While a heavier vehicle at times needs more energy - trains are a counter example to consider. Magnitudes heavier, but do not need magnitudes more fuel.

Which comes to Newton's laws of motion, the two concepts of inertia and Newton's second law: "F=ma", come into play. If the course is a straight 100 mile segment with no elevation gain - then the dominant fuel expenditure will be counter-acting aerodynamic drag. When trains haul many cars, the train cars are drafting behind one another, meaning those cars do not need any force to overcome drag, just the lead car needs to do that.

So, places where trains do badly, will be places where weight matters. Urban environments when stopping/starting a lot - trains will keep it slow. Very hilly/mountainous courses - trains "nope" that and require shallow grades. Which goes to show, if you're spending most of your time fighting gravity - then weight is really important, if most of the time is fighting aerodynamic drag, then weight becomes less important as aerodynamic drag decreases. For example, it does not matter as much how heavy a bullet train is, the drag coefficient is a better indicator of overall fuel cost rather than carry weight.

I'd love to see how you derive that from Newton's Laws of Motion, which are all about acceleration. All other things being equal, it takes no more or less energy to keep a heavy object in motion than a light one. After all, a pendulum's period is proportional to its length, and not its weight.