I dislike the radiator being considered a standard part of the outline of the engine compartments due to mid engined cars and oddballs like the 5cyl audis, not to mention 1/2 width radiators found on many hondas and a few other cars.

in the case of the miata - yeah, a fine, common sensical boundary, but I think we should be clear with ourselves that it is not a valid definition in MANY cases.