Stuck in traffic jam for two hours. Watched the charge gauge drop down to three bars. Gas engine wasn't being called often enough to keep a normal level of charge. Car stopped. No gas drive or electric motor drive. Put it in neutral, nothing. Put it in sport mode and engine started. Got through the traffic jam and once the battery had been charged up to a normal level I put it back in drive. Now everything back to normal. Off to the dealer today to see if any abnormalities were recorded on the computer.