Rental car classes are not standardized. Each company assigns its own internal codes (ACAR/ICAR/SUV/MVAR/PCAR in industry shorthand), then markets them under marketing names that drift over time. RentWise normalizes the six classes that matter for the vast majority of trips: Economy, Midsize, SUV, Minivan, Luxury, and Van/Cargo. Compact and full-size sedans get folded into economy and midsize because real-world fleet substitutions blur those lines anyway — book a midsize and you might receive a Camry, a Malibu, or a Sonata depending on what the lot has that hour.
Economy cars are the cheapest line on every quote and almost always come with the best fuel economy, but the trunk swallows two carry-ons and that is it. Midsize is the sweet spot for two adults plus checked luggage. SUVs are not just for off-road — at most US airports they are the only class that comfortably seats five adults with luggage. Minivans are the least glamorous and most practical option for groups of six or more. Luxury sedans buy you a quieter cabin and stronger highway power for client-facing or special-occasion trips. Van/Cargo classes are the only realistic option for sports teams, large group transfers, or moving heavy gear.