In the case of cars with infernal combustion engines, it's even worse. Even for very efficient road car engines, more than 50% of the energy in the fuel is expelled as waste heat, through either the exhaust or cooling system. Of that smaller than 50% fraction, indeed most of the energy is spent overcoming aerodynamic drag of the car body, and friction from the tires.
Sidenote: F1 made headlines a while back they had achieved >50% thermal efficiency, with an incredibly complicated hybrid system that recovered excess exhaust energy from the turbo.

It makes sense for everybody, except for those with a financial interest in selling and/or haggling over software licenses. That's not only the companies producing the actual software, but also legal firms and similar "specialists" who siphon off money from this system of complex IP law.
IMO the only way to transition to more software being open sourced, is to deconstruct these vested intrests with regulation. We need to fundamentally restructure the way software development is funded, and transition away from a model where ownership is the only thing that's profitable.
Doing that is delicate though, because as backlash from those vested interests, a lot of workers will likely lose their jobs. You need to make sure those people easily find new jobs working on open source, and communicate that effectively, so workers' job insecurity is as low as possible during the transition.