2010 Chevrolet Suburban 2500 Owner's Manual - Page 176

D (Drive): This position is for normal driving. It provides the best fuel economy. If you need more power for passing, and you are: . Going less than about 35 mph (55 km/h), push the accelerator pedal about halfway down. Going about 35 mph (55 km/h) or more, push the accelerator all the way down. By doing this, the vehicle shifts down to the next gear and has more power. If the shift stabilization feature determines that a current vehicle speed cannot be maintained, the transmission does not upshift and instead holds the current gear. In some cases, this could appear to be a delayed shift, however the transmission is operating normally. The vehicle's transmission uses adaptive shift controls. Adaptive shift controls continually compares key shift parameters to pre-programmed ideal shifts stored in the transmissions computer. The transmission constantly makes adjustments to improve vehicle performance according to how the vehicle is being used, such as with a heavy load or when the temperature changes. During this adaptive shift control process, shifting might feel different as the transmission determines the best settings. When temperatures are very cold, the Hydra-Matic ® 6-Speed transmission's gear shifting could be delayed providing more stable shifts until the engine warms up. Shifts could be more noticeable with a cold transmission. This difference in shifting is normal. . D (Drive) can be used when towing a trailer, carrying a heavy load, driving on steep hills, or for off-road driving. You might want to shift the transmission to a lower gear selection if the transmission shifts too often. Downshifting the transmission in slippery road conditions could result in skidding. See Skidding under Loss of Control on page 5‑11. The vehicle has a shift stabilization feature that adjusts the transmission shifting to the current driving conditions in order to reduce rapid upshifts and downshifts. This shift stabilization feature is designed to determine, before making an upshift, if the engine is able to maintain vehicle speed by analyzing things such as vehicle speed, throttle position, and vehicle load. 3-36