Positive ground car

Both vehicles are grounded that's for sure

My dad once had a car with positive ground. If I recall correctly it was a British car, the Mayflower. Like most British cars of that era, it had positive ground, meaning that the positive terminal of the battery was connected to the chassis. New cars, in particular the Japanese cars popular in Malaysia, had by then negative ground. The first time this caused an issue was when my dad decided to have a radio/cassette player installed. The preponderance of negative ground meant that radios were designed for that. The man who fitted the radio had to improvise a wooden panel to mount the radio on so that its case could be insulated from the car chassis. As you can imagine, I thought this a little unsatisfactory as it meant that the radio case was "live" and could cause shorts of the car battery to the chassis.

Later, at my behest, my dad got a car mechanic to reverse the polarity of the car's electrics. I think even the generator connection didn't need to be reversed as the excitation coil was reversed too, but I'm not certain (that era of cars did not have an alternator). Remember, the radio was probably the only electronic device in a car in those days.

All cars nowadays have negative ground, and the dual standards are a footnote in history. I read arguments for one or the other based on galvanic corrosion or something like that but I'm not convinced. The car is a floating electrical system anyway.

PS: There was another divide, the 6V and 12V battery cars. The only 6V car I knew of at the time was the Volkswagen. Again most cars standardised on 12V after that.