Apparently it has a capacitor in it, to improve the power factor. Higher power factors are better, for AC circuits (less resistance losses in the wiring), but cars are DCand even worse for us, bikes (all the ones I know anyway) run a shunt regulator, which just turns all the excess power generated from the stator to heat anyway. So for us, a switch-mode reg is something that would increase power and fuel efficiency [1]
[1] by less than an eighth of fuck all
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