Mercedes-Benz has slyly revealed a lightly facelifted version of the 33-year-old G-class prior to its planned public premiere at the Beijing motor show next month. The reworked version of the German carmaker's iconic military-grade SUV, planned to go on sale in European markets in June with North American deliveries slated to begin by the end of this year, can be seen in the background of an official photograph of the facelifted GLK posted on the Mercedes-Benz media Web site. Among the subtle changes made to the G-class's classic square exterior is a restyled grille with three prominent slats in place of the older model's seven slats, new headlamp inserts with horizontally mounted LED running lights and redesigned mirror housings. Not seen in the picture but also evident in recent spy photos of prototypes testing on public roads are altered tail lamp graphics and a new line of alloy wheels. Official information has yet to be released, but insiders confirm that both of the G-class's standard engines are retained for the 2013 model year, including the 383-hp naturally aspirated 5.5-liter V8 and the 208-hp, 3.0-liter V6 diesel. Up until now the diesel powerplant has not been offered in North America. Further up the lineup, the 12-year-old G55 AMG's 500-hp supercharged 5.4-liter V8 finally makes way for a 536-hp version of Mercedes-Benz performance division AMG's twin-turbocharged 5.5-liter V8 in a new G63 AMG. The big news, however, surrounds the addition of a new G65 AMG range-topping model to the lineup. It runs the same twin-turbocharged 6.0-liter V12 recently confirmed for the SL65 AMG. With 621 hp and a sturdy 737 lb-ft of torque, it is claimed to propel the 5,500-pound-plus G65 AMG from 0 to 62 mph in 5.2 secconds. Top speed is limited to 155 mph. The G65 AMG will be the first G-class model to receive V12 power. The new AMG models receive different front-end styling from the standard G-class model, with a deeper front bumper housing large air ducts for more efficient engine cooling. Other performance changes include larger brakes adopted from the ML63 AMG. Unclear at this stage is whether the G63 and the G65 AMG will continue to flaunt the extravagant side pipes used on the G55 AMG, although early prototypes seem to suggest that they will. In a move that promises to bring substantial fuel savings to all models, the reworked G-class will use Mercedes-Benz's seven-speed 7G-tronic gearbox in place of the older five-speed 5G-Tronic unit in use since 1979. Autoweek sources say the new gearbox will offer an automatic stop/start function along with brake-energy recovery, but only on the G63 AMG. Other upgrades brought to the G-class, which continues to carry the internal code name W463 and is produced by Magna Steyr in Austria, is a revised instrument cluster bought over from the third-generation M-class, a 4.5-inch color monitor and Mercedes-Benz's latest COMAND system that incorporates Internet-based functions. The facelifted G-class will continue to be offered with the choice of two wheelbases, 94.5 inches in standard guise and 112.2 inches in long wheelbase form. The quirky cabriolet is also set to continue but only in combination with the standard 383-hp, 5.5-liter V8 as the G500 cabriolet.