With a total of 15 different models and four body configurations, the 3 Series is BMW most versatile model. While the M3 is the most powerful of the 3 Series models, the twin-turbocharged, all-wheel drive 335xi might be the most exciting to drive. All 3 Series convertible models offers a quiet ride and coupe-like look due to a retractable hardtop. During the first four years of ownership, BMW 3 Series drivers receive a 50,000-mile warranty and $0 maintenance program in addition to an unlimited mileage roadside assistance. The BMW 3 Series gets an estimated 25-28 mpg on the highway; the M3 model tops out at 20 mpg.