> synthetic fuels can't compare with battery EVs in terms of energy efficiency,
This is almost meaningless. If you are turning renewable energy sources into either synthetic fuel or grid power, then efficiency is irrelevant. What matters is cost (of the whole system, including distribution of the energy) and emissions (burning even carbon-neutral methane or hydrogen isn’t quite zero emission). There are startups working synthesizing fuels from air and solar energy, and they argue, fairly convincingly, that bypassing the entire electrical distribution network can more than make up for extremely low efficiency.
Also, heavier vehicles likely emit more brake and tire dust than lighter vehicles, and a series hybrid can be much lighter than a long range BEV.
Of course efficiency matters, because electrical energy is a bottleneck resource. Renewables may be cheap, but they aren't free and we have a lot of other things we need that energy for. If you can make a car go 4 miles with 1kwh of electrical input, that's much better than a car that can got 2 or 3 miles with the same input. Multiply that by the ~1.5 billion cars/trucks in the world presently and that's a huge difference.
Burning liquid fuel in a heat engine typically wastes about 2/3 of the chemical energy as heat. Hybrids do better, but there's only so much you can do.
I don't know what the state of the art for synthesizing liquid fuel is, but I assume there's some significant energy loss there too.
On the other hand, modern permanent-magnet electric motors can be around 95% efficient. Lithium ion batteries typically have coulombic efficiency better than 99%. Actual energy efficiency is a little less due to internal resistance (it takes a higher voltage to charge the battery than you get out when you drain it, so even if amp-hours in is almost equal to amp-hours out, watt hours might be a little different). Charging circuitry also tends to be pretty efficient. Battery-electric drive trains are already so close to optimal efficiency that there's very little that they can actually be improved on, and nothing else comes close.
The tire dust microplastics thing is a real problem, but it's not that much worse for EVs than other cars. Brake dust is much less of an issue on BEVs and hybrids, due to regenerative braking.
Personally I hope the idea of BEVs that haul around 800 pound batteries goes out of fashion (and it might if we could be bothered to electrify our major highways to make huge batteries largely unnecessary), and I also hope cars in general start to get smaller and less numerous. But I think cars are basically here to stay in some form, so they might as well be electric.
This is almost meaningless. If you are turning renewable energy sources into either synthetic fuel or grid power, then efficiency is irrelevant. What matters is cost (of the whole system, including distribution of the energy) and emissions (burning even carbon-neutral methane or hydrogen isn’t quite zero emission). There are startups working synthesizing fuels from air and solar energy, and they argue, fairly convincingly, that bypassing the entire electrical distribution network can more than make up for extremely low efficiency.
Also, heavier vehicles likely emit more brake and tire dust than lighter vehicles, and a series hybrid can be much lighter than a long range BEV.