Re: reverse polarity
Correct, many English cars back in the day had positive earths. Lucas designed them that was so the components would protect the fuses but letting their smoke escape first. (and if you believe that one I have this prime Florida land with lotsa Cypress and Mangrove). Many also had two six volt batteries instead of one 12v and in inaccessible locations.
Americans hid fuel fillers, windshield wipers, and radio antennas. The Brits hid the batteries.
However the Crossfire is German so uses a proper 12v battery in a proper location. The Group Size is H6 and are available many places
Anymore I buy only AGM batteries. About a 50% cost premium for 3X the life.
ps anything that sits for more than a week (anything not in the front garage) has a $5 float charger on it. They always start right up, even the diesel.