They can
A Toyota Prius can, IF it or any plug-in hybrid is charged with commercial electric power from a coal-fired power plant.
I quantify this in CO2 per mile.
If per mile it burns a 20th of a gallon of gasoline not only will it add CO2 to the atmosphere but the amount in weight it adds can be more than the weight of the fuel.
If per mile it expends energy collected from solar or wind, fuel pollution is nearer zero.
Fine. BUT !
All that inefficiency that you cite is Carbon free.
Hydrogen seems like an absolutely dandy fuel. BUT !
Recent reports indicate storing Hydrogen adequately is easier said than done.
Jeremy Rifkin in The Hydrogen Economy says fuelizing Hydrogen is often accomplished by electrolysis of water, H2O.
Problem is, for the amount of energy input into the process, only 70% is retained.
So we need a more efficient means to supply the amount of Hydrogen needed. AND !!
Let's not forget Hindenburg.
While it is true that wind/solar can be totally clean, but not only is the US only 15% wind/solar, also bio fuels like palm oil actually reduce CO2 by absorbing more when grown than is released when burned.
So bio fuels are much better than wind/solar.
By better I mean much cleaner, cheaper, lighter, less flammable, etc.
We know hydrogen is not that hard to do because Iceland has been doing it for decades.
It is true hydrogen is hard to contain, but what Iceland does is generate it on the fly.
While a filled up car will lose its hydrogen in a month or two, that is not that big of a problem.
And it turns out hydrogen is not a fire risk.
The reason is it dissipates and rises too quickly to ever be a fire problem.
They say the Hindenburg was actually due to the flammable aluminum and varnish paint that was used.
While generating hydrogen has its inefficiencies, it is much more efficient than batteries.
Batteries are the worst possible, since they are expensive, heavy, slow, limited capacity, a fire hazard, and rare earth elements like lithium.
We could also use solar/wind to generate something else, like methanol.
Lots of options.
But the way we are headed is batteries, which is the worst possible.