I don't have any facts, figures or graphs but here's what I know based on migrating to USA Lite from Germany as a seven year old. North American tastes in bicycles, automobiles and motorcycles provided more than a little bit of a culture shock in a cartoonish way.
Things I didn't see on bicycles back home: handlebar streamers, ape hangars, banana seats, sissy bars, small front wheel/large back wheel combos, squared off slicks, excess chrome and paint.....it wasn't long before these technical delights made their way to HD and the highly profitable Japanese clones. Give the people what they want.
Domestic cars for the first 9 decades of the industry: Oversize, overweight, softly sprung, under damped, gas guzzling, styling cued whore mobiles. Of course the true motoring enthusiast could modify these atrocities with the latest engineering tricks and available speed parts. eg, take a 5000lb 427 Chevy Impala, raise the back sky high for big drag race gumballs, 3 inch tires on front and Cherry Bombs.
Motorcycles: What can I say? Please reference HD bashing for refresher if needed.
Generally speaking history will show Axis vehicles are either sparse utilitarian or drivers machines where form follows function and Allies the reverse. Not that there's anything wrong with that.