C-H, your comment about car batteries in the boot reminded me of an incident back in 1986. My middle-school (7th grade) math teachers comes to work with a bandaged finger.
After class I ask him what happened and he told me he was changing the battery in his car (an Audi) and got his finger pinched when he moved the driver's side chair to get to the battery.
Since I was always used to seeing car batteries in the engine compartment I was somewhat confused. That's when he told me that the Audi designers put the battery in the passenger compartment - somewhere under the seat...
Years ago I also seen some buses with the battery (a huge 24 volt block with eight or 10 of those yellow screwcaps to access the cells) in the passenger compartment. It sat between the driver's chair (a bit under the chair) and the wall to his left.
Manufacturers may have polished things a bit better now and hidden the battery. These were old 1960s municipal buses.
On some small trucks it hangs on a tray from the bottom of the truck body.
