General Motors Corp. has extended until Sept. 30 its employee discount deal for everyone, continuing a limited incentive program that has helped clear out inventory, particularly for pickup trucks and SUVs, and softened an expected drop in sales.

The discount was offered to everyone Aug. 20 as part of GM's 100th anniversary celebration and the incentive program is expected to have made an impact on August sales totals when they are released later today.

GM, Ford Motor Co. and Chrysler LLC are expected to sustain further market share losses in August as domestic automakers continue to bear the brunt of the slump in demand, largely because all three have truck heavy lineups. GM's sales slid 26.1 percent in July and are down 17.7 percent through July.

Jesse Toprak, pricing and market analyst at Edmunds.com, an online automotive research site, said GM sales were down sharply earlier in the month before the plan was introduced.

The employee pricing deal applies to all 2008 vehicles in stock, except for medium-duty trucks.

The 2009 vehicles eligible for the discount include: Chevrolet HHR, Cobalt, Malibu, Impala, Equinox, Avalanche and all models of Silverado pickups; Buick Enclave; Pontiac G5 and G6, Vibe, G8, Solstice and Torrent; GMC Acadia and all models of Sierra pickups; Saturn Aura, Sky and Outlook; Cadillac CTS, SRX, DTS and STS; HUMMER H2 and H3 SUV. The hybrid models of those vehicles also are eligible.

The deal excludes 2008 medium-duty trucks.