General Motors will unveil at next month’s North American International Auto Show in Detroit the ’13 Chevrolet Sonic RS, a higher-performance variant of the recently launched small car.

GM says the 5-door Sonic RS, which the auto maker first showed as a “hot-hatch” concept car two years ago, will go on sale in late 2012. Pricing has not been announced.

The B-car will receive mostly cosmetic enhancements, sticking with same 1.4L turbocharged 4-cyl. engine making 138 hp available in regular-production versions of the Sonic. A 6-speed manual and 6-speed automatic transmission will be available.

The sole mechanical upgrade will be a lowered and stiffened suspension with higher-performance dampers.

The exterior of the Sonic RS will get a unique front fascia with a specific fog lamp design, a different rear fascia and a model-specific grille.

Other enhancements include new rocker moldings, unique mirror cap finishes, a retuned exhaust note and chrome tip, RS badges and specially styled 17-in. wheels with five spokes.

Inside, the Sonic RS will feature sportier seats, a race-inspired steering wheel with a flat bottom, special shift knob for manual models, aluminum sport pedals, unique gauges and RS badging on the instrument panel and door inserts.

GM started production of the Sonic 5-door and sedan at its Orion Twp., MI, assembly plant earlier this year.