Bringing a car into the US from Canada is described as trivial (a signed registration and a roughly $15 border fee), while taking one the other way, or through post-Brexit Europe, is far costlier. Euro cars carry a US/Canada 'Federal' safety tag that buyers ask about for border compliance, and German re-import demands an original (non-photocopy) title.
Importing from Canada and Europe — logistics and the 'Federal' tag
Mercedes-Benz 230/250/280SL Pagoda (W113) · ownership