AFAIK the overall issue with fuel efficiency is still not fixed? Even small vehicles rip through both liquid fuel tanks and storage batteries like they were nothing.
Moreover solar panels charge rate is very low now. I had to hack my local jsons just so that an APC covered with panels could do much more than keep up with the minifridge drain (while not moving…). Even with that, it will still burn through a set of 4 large storage batteries in some fairly short hops. I’ve gotten used to just driving a few blocks each day rather than ever doing longer trips, without hacking the solar panels, I don’t think you could use a larger vehicle at all - which could be the intent?
At any rate in addition to the far lower efficiency, electric motors can barely go at 34 kph with an APC and can’t drive over a bush. Probably realistic, but not terribly fun. 
The real problem is that even if you go with a gas/diesel engine, you’ll generally be draining it off about as fast as you can siphon gas out of cars you pass. I don’t mind gas being a precious commodity, but I’d rather it be treated as a rarer find with a much higher energy density than a common find that you have to go through like Niagara Falls. It’s logistically aggravating and makes vehicles a lot less fun when you have to spend half your time humping around a steel can and a hose.
Either way the deathmobile is now reduced to a very slow moving logistical base that you kind of crawl around in as a matter of necessity, not so much with the rolling engine of awesome.
So, more realistic in terms of it being difficult to keep an APC fueled in the apocolypse, but kind of unrealistic in that gas is very common - but seems to provide an energy density closer to that of cord-wood insofar as engine efficiency goes. 
