Castenea wrote:Steam will work for as long as the proscriptions are in effect, but electric has problems with range and recharge time. Electric vehicles will be a niche item as long as ranges on full charge are under 100 mi, and recharge times are measured in hours. As a comparison most cars sold in the US today have a range of 250 to 300 mi on a full tank and can fill the tank at most service stations in under 15 min.
With Federation tech? Where you've got man-portable fusion plants that run for years and years with apparently zero maintenance after being left in a cave for a thousand years? Electric is pretty obviously the way to go, there, unless the Federation has some sort of direct-momentum-transfer field technology or something.
With-proscriptions, look at the Stanley Steamer; a steam automobile can be quiet, safe, and efficient. No need to develop IC engines. (Stirling engines also a possibility. )
Post-proscriptions, direct ammonia fuel cell electric cars would be a good first step for Safehold; ammonia is an easy to handle pumpable fuel, safer than gasoline (gaseous ammonia won't explode at STP), and you can make it from air and water using a catalytic process that's about 70% efficient. (Presumably using your first big ugly go at a fusion plant for power as the tech bootstrap gets going.) Since the fuel-cell-electric drive train is about 70% efficient as well, even without regenerative brakes, you do fine on range; drive-train total mass is less than gasoline engine drive trains.
Then you've got an electric car industry that you can swap whatever Federation highly-compressed-tank-of-electrons tech applies into once you can make those. The ammonia production can then all go to agriculture.