After four full years on the market, you'd think someone would have come up with an entry-level luxury car to rival the current BMW 3 Series. Perhaps by now an automaker would have bribed a BMW engineer to fork over the blueprints, or maybe had its CEO take a 3 Series, hand it to his engineers and say, "Here, copy this." Indeed, the 3 Series is often imitated, but somehow it's never been duplicated. For unparalleled driving excellence, the 2010 BMW 3 Series is still where it's at. As is typically the case, BMW has relentlessly improved this 3 Series since its debut in 2006. For '07, the 335i's twin-turbocharged inline-6 debuted, an engine that has been showered with critical praise ever since, and a sleek coupe and retractable-hardtop convertible also joined the lineup. For '09, the sedan and wagon's controversial taillight design was rectified, and a gloriously torquey and fuel-efficient turbodiesel inline-6 became available for the sedan. Heck, BMW even managed to fix iDrive last year, thanks to a proliferation of physical buttons and a much-improved menu structure. All of that partly explains why the 3 Series is still the most desirable car in its class, even at the ripe old age of five. The other part is the inherent goodness of its chassis. Quite simply, no other entry-level luxury model can match the 3 Series' exquisite combination of athletic handling and premium ride comfort. Even the base suspension setup is more capable than most, but the Sport package really brings the 3 into focus, giving it sports-car-grade cornering capabilities without the slightest hint of impact harshness. The performance numbers are impressive in themselves, but this car transcends them -- it feels even more confident and composed than those numbers suggest. The 2010 BMW 3 Series has long been America's best-selling luxury car, and we see no reason why it won't retain its crown. Automotive journalists and consumers agree that the 3 is the segment leader, which highlights its irresistible appeal to enthusiasts and casual drivers alike. There are worthy rivals, of course, including the powerful Infiniti G37, the striking Cadillac CTS and the Euro-chic Audi A4. But even as the twilight of this model's production run approaches, the 3 Series continues to reign supreme.