You should be able to post responses to bidder questions to the listing. You could get a friend with an eBay account to ask a question on the listing like "What are measurements XYZ?" and you post the response.
A $200k car doesn't have to look ostentatious. It only has to look that way if you go ultra-sporty. GT cars, ultra-lux (Rolls, Bentley) and the like look nice (just like a hyper expensive watch) but you have to know what you're looking at to really know what it costs.