In contrast to most production hybrids, which use a gasoline piston engine to provide additional acceleration and to recharge the battery storage, the Volvo ECC used a gas turbine engine to drive the generator for recharging. This type of engine has a higher thermodynamic efficiency than the conventional internal combustion engine with pistons.
This contrasts with most production hybrids, which use a gasoline piston engine to provide extra power and recharge the battery. In contrast, the Volvo ECC utilized a gas turbine engine to drive the generator for recharging, resulting in improved thermodynamic efficiency over traditional piston-based engines.