Efficient Gasoline engines come in at 25-30% efficient, Diesel somewhere around 35%. Hybrids can boost that some, because they can scavenge energy that'd otherwise be lost, but only somewhere between 5 and 15% in real world scenarios.
https://www.motortrend.com/uploads/2022/08/Screen-Shot-2022-...
It would be nice to get that last 20% efficiency back but I haven't found it.
You could also, similarly, subvert the car entirely and just disconnect it from the car, charge it from the panels/DC converter, and reconnect it when finished.
On a side note, I don't want to necessarily fast charge the car; I just want to use the electricity from my solar panel in the most efficient possible way; that would be heating water, powering stuff in the house and charging my car; the last of which probably would take the most electricity.
Pure BS. Tesla is at 95% from outlet to battery on 240V, and it can be even more (depending on the need to run cooling/heating).
Grid transmission losses average at around 5% nationally, but it heavily depends on the location.