A vehicle includes an engine, an electric machine, a disconnect clutch, a starter motor, and a controller. The engine and electric machine are each configured to generate power to propel the vehicle. The disconnect clutch is disposed between the engine and the electric machine. The controller is programmed to, in response to a command to start the engine, operate either the disconnect clutch or the starter motor to start the engine based on a level of adaptive learning of previous disconnect clutch engagements.