Bongo Fury

found it in the passenger footwell and cant see an obvious place for it to go back into ..

No idea but, if it's anything like mine, there are loads of unknown wires. I reckon the original Japanese owner must have had every possible accessory fitted and removed

Its looks very much like a 12 volt power cable and plug, in fact that style of plug is often used on radio equipment, CB / Amateur / PMR etc.