2005 Mercedes SL-Class Owner's Manual - Page 175

Controls in detail Automatic transmission i You cannot shift with the steering wheel gearshift buttons when the gear selector lever is in position P, N or R. The last selected program mode (C or S) is switched on when the engine is restarted. Downshifting Warning! Upshifting G Press the outside of one of the buttons 2 on the steering wheel. The transmission will shift to the next higher gear as permitted by the shift program. This action simultaneously extends the gear range of the transmission. On slippery road surfaces, never downshift in order to obtain braking action. This could result in drive wheel slip and reduced vehicle control. Your vehicle's ABS will not prevent this type of loss of control. Press the inside 1 of one of the buttons on the steering wheel. The transmission will shift to the next lower gear as permitted by the shift program. This action simultaneously limits the gear range of the transmission ( page 167). 173