DETROIT --- The 2008 Chevrolet Tahoe Hybrid and the 2008 GMC Yukon Hybrid are the first personal-size vehicles featuring an advanced two-mode hybrid powertrain. The powertrain was developed cooperatively by General Motors, BMW and DaimlerChrysler. GM said the hybrid versions of the Tahoe and Yukon get about 25 percent better fuel economy, but can still haul seven or eight passengers plus cargo. They can also tow up to 6,000 pounds. GM's two-mode hybrid system has been used in transit buses since 2003. But the 2008 Chevrolet Tahoe Hybrid and GMC Yukon Hybrid mark the technology's first application in a personal-size vehicle. The two-mode hybrid system integrates electric motors, high-performance electronics, wiring, energy management and hybrid system control units, according to a report by Edmunds.com.