Cars are categorized as "subcompact" (aka "economy"), "compact", "midsize", and "full size". These designations certainly infer a variation in size, i.e., in passenger and luggage carrying capacity. Thus, the best way to prevent customer disappointment and provide a common expectation would be to have cars categorized uniformly throughout the industry, according to a set standard based on number of pax and pieces of luggage each make and model can carry. Would do away with the existing sizing discrepancies between different companies. Fancy cars could just have "Luxury" or similar added to the appropriate size.

Am I off-base with my thinking?