with partial opening, all other windows are fixed - Full reinforced structure and suspension to hold extra weight - SLS (self leveling rear suspension) - Microphone with external speaker (optional) - Users manual includes a Special Protected Vehicles B4/B6 booklet. - Datacard codes for GUARD lists 979 - Safety Version added with Z04 - B4 Reinforcement on Special Protection Version or Z06 - B6 Reinforcement on Special Protection Version. 4MATIC all-wheel drive option In 1997, Mercedes-Benz reintroduced the 4MATIC all-wheel drive system in the US on the W210, although it was previously available in some European territories. Although this 4Matic system shares its name with the 90's 4MATIC system of the W124 300E, the system was totally redesigned and simplified. Rather than using the clutches and couplings of the earlier design, Mercedes opted to use three open differentials: front, center, and rear. The front suspension design of the 4MATIC-equipped models is different from the rear wheel drive models and makes some replacement parts (such as shock absorbers) more expensive. The E 55 AMG was available on request with 4MATIC option, based on the driveline of the E 430. Reliability concerns Some known problems include the front spring perch being corroded and tearing away from the inner fender (wing), causing the front suspension to collapse. (4Matic models are not believed to be affected.) Other problems include defective harmonic balancer pulleys (recall), rust on trunk lid near latch, rust on Mercedes emblem on front hood, rust on door frames under window seals (recall), rust on front wings just above bumper, defective mass airflow meter, melted rear light bulb sockets, defective blower motor regulators, and rear window regulator failures. Harmonic Balancer - Some M112 and M113 engines used in W210 models were equipped with a harmonic balancer pulley which, due to a supplier quality problem, may fail and cause engine damage. If the rubber insert of the harmonic balancer pulley delaminates, the pulley may grind through the timing chain cover and oil pan, causing several thousand dollars of damage. Mercedes-Benz USA issued Service Campaign #2005-020003 which included inspection of the part and replacement if necessary at no cost. The part number on the harmonic balancer pulley can be compared to those given to Mercedes-Benz dealers in the Service Campaign notice to determine if the part is a faulty original or has been replaced with the updated part. Replacement of the faulty part with