No other MODERN vehicle has this amazing feature.
I beg to differ, 2005 Buick Le Sabre has the battery under the rear seat.
It is a special type of vented battery, it is vented out via hoses through the floor boards.
Expensive to replaced. 50 bucks more than a normal battery.
There are terminals under the hood to connect to if it needs a jump.
At one time in my 54 panel I had both a 12v battery and a 6v battery.
The 6v was in the original location and the 12v was mounted on the passenger side fender skirt.
On the engine was the original 6v generator and a 12v alternator with a built in regulator, both turned using the same fan belt.
I used the 12v battery to power a 12v high wattage sound system.
The 6v battery was used for the trucks original electrical system.
Both batteries shared the same ground.
With engine off, after a couple hours the 12v battery would drain down dead.
I would kid everyone that we were stranded.
Then I would hop in the truck and start it up with the 6v battery.