The Schatz Heat Battery stores excess heat energy from the engine cooling system during vehicle operation. This excess energy may be returned to the coolant upon the ensuing cold start, shortening the engine warm-up period and decreasing cold start related emissions of unburned fuel and carbon monoxide (CO).A Heat Battery was evaluated on a test vehicle to determine its effect on unburned fuel emissions, CO emissions, and fuel economy over the cold start portion (Bag 1) of the Federal Test Procedure (FTP) at 24°C and -7°C ambient conditions. The Heat Battery was mounted in a vehicle fueled alternately with indolene clear (unleaded gasoline) and M85 high methanol blend fuels. Several Heat Battery/coolant flow configurations were evaluated to determine which would result in lowest cold start emissions.The greatest reductions in Bag 1 unburned fuel and CO from stock levels occurred during testing at -7°C with M85 fuel and a 60-second period of coolant circulation prior to starting the engine. Reductions in Bag 1 unburned fuel and CO from the stock configuration were greater than 80 percent. Fuel economy over Bag 1 increased during this lower temperature testing by almost 20 percent. The Heat Battery also caused reductions in unburned fuel and CO emissions at 24°C conditions, though these reductions were lower than those noted during -7°C testing.