10% market share is a ludicrous figure on which to base any projections.
GM, Ford, Chrysler, Toyota each hover around 15% market share. Nissan and Honda are each less than 10%.
Mercedes, about 2.5%
Porsche, BMW? They're not even on the radar. Probably less than 1% each, and they've been building cars for a while.
Where do you suppose Apple would fit in? Is Apple the Chevy of computers, or the Porsche?
10% US market share of automobiles is "moderate success". Really?