DETROIT – BMW AG introduces the ’12 1-Series M Coupe and 650i convertible at the North American International Auto Show here.

The newest M model will be powered by a 3.0L I-6 with twin-turbochargers and features a specifically tuned version of the current M3’s aluminum suspension.

The 1-Series M also has a substantially widened track and a metal roof panel that weighs 35 lbs. (16 kg) less than the moon roof in the standard 1-Series. Reducing weight at the tallest point of the vehicle lowers the car’s center of gravity to improve vehicle dynamics.

The 650i convertible features a classic soft-top roof and is powered by BMW’s 4.4L turbocharged V-8 that makes 400 hp and 450 lb.-ft. (610 Nm) of torque. Two transmissions are available: a standard 6-speed manual and optional 8-speed automatic with steering wheel-mounted paddle shifters.

As with the previous version, the new 650i convertible features a super-insulated folding soft-top that can retract in 19 seconds at vehicle speeds up to 25 mph (40 km/h). The interior features a fresh design with more passenger space, improved ergonomics, and lush materials, including optional full-leather trim with contrast stitching.

The 1-Series M Coupe will base price at $47,010, while the ’12 BMW 650i convertible will start at $91,375. Prices include an $875 destination charge. Both cars go on sale in the U.S. in the spring.

BMW says other ’12 1-Series models will be priced as follows: 128i Coupe, $31,825; 135i Coupe, $39,925; 128i Convertible, $37,475; and 135i Convertible, $44,675. All prices include an $875 destination charge.

The BMW Group (including Mini) says it posted strong sales gains in the U.S. last year, especially with its cross/utility vehicles and Mini brand. Total deliveries jumped 9.9% to 265,757 units, compared with 241,727 in 2009.

BMW brand sales climbed 12% to 220,113 units, compared with year-ago’s 196,502. In December, best-selling vehicles included the 5-Series, up 28.9% to 5,045 units; 3-Series, up 12.3% to 10,067; X5, up 12.1% to 3,939; and X6, up 52.8% to 859.

Overall, despite its sexy car lineup, BMW says its CUV models (the X3, X5, X6), were among its best sellers, up 26.9% for the year to 48,108 units, compared with 37,925 in 2009.

Mini USA reported 4,320 deliveries last month, a 23.8% hike from 3,489 in like-2009, making it the most-successful December ever for the brand in the U.S.

Total calendar-year sales for 2010 were 45,644 units, a 0.9% uptick from 2009.