There are several different types of hybrid powertrain available on modern cars, each providing different levels of electrical assistance to a gas-powered motor. The mild hybrid, also known as the 48-volt hybrid, relies the least on its electric motor. A full hybrid or plug-in hybrid features an electric motor that’s capable of driving the car under its sole power, but with a mild hybrid, the electric motor can only provide limited assistance to the combustion engine. That assistance is mostly called upon when the car is first taking off from stationary, providing a boost at stop lights or in traffic.
Each mild hybrid system varies by manufacturer — some are so mild that most drivers will barely notice they’re there, whereas some perform more of an active role in low-speed acceleration. This, in turn, affects the efficiency of each system, although the EPA estimates that a mild hybrid improves efficiency by around 3-6% on average.
