4. Mazda Autozam AZ-1
The Mazda Autozam AZ-1 emerged as one of Japan’s most distinctive kei cars, designed specifically to adhere to the nation’s strict regulations on vehicle dimensions and engine displacement. Under Japan’s kei car laws, compact vehicles that fell below certain size and engine limits qualified for significant reductions in taxes and insurance fees. Mazda embraced these constraints, creating the AZ-1 with a minuscule 657cc turbocharged engine and an incredibly compact body. Its dramatic gull-wing doors and sporty styling made the AZ-1 a standout in a category usually dominated by practicality, showcasing how legal constraints can inspire truly imaginative automotive design.