1994 GMC Sonoma Owner's Manual - Page 172

Run your engine only as long as you must. This saves fuel. When you run the engine,make it go a little faster than just idle. That is, push the accelerator slightly. This uses less fuel for the heat that you get and it keeps the battery charged. You will need a well-charged battery to restart the vehicle, and possibly for signaling later on with your headlights. Let the heater run for awhile. Then, shutthe engine off and close thewindow almost all the way to preserve the heat. Start the engine again and repeat this only when you feel really uncomfortable from the cold. But do it as little as possible. Preserve the fuel as long as you can. To help keep warm, you can get out of the vehicle and do some fairly vigorous exercises every half hour or so until help comes. Recreational Vehicle Towing (Four- Wheel Drive Only) If your vehicle has 4-wheel drive, you may tow it behind another vehicle providing it does have the optional electronic shift transfer case. not NOTICE: Recreational vehicle towingis not recommended for vehicles with the optional electronic shift transfer case because the electronic shift has no neutral position. 4-36