ICE torque output is minimal at lower RPMs and conventional vehicles increase engine size to meet market requirements for acceptable initial acceleration. The larger engine has more power than needed for cruising. Electric motors produce full torque at standstill and are well-suited to complement ICE torque deficiency at low RPMs. In a power-split hybrid, a smaller, less flexible, and more efficient engine can be used. The conventional Otto cycle (higher power density, more low-RPM torque, lower fuel efficiency) is often modified to an Atkinson cycle or Miller cycle (lower power density, less low-rpm torque, higher fuel efficiency; sometimes called an Atkinson-Miller cycle). The smaller engine, using a more efficient cycle and often operating in the favorable region of the brake specific fuel consumption map, significantly contributes to the higher overall efficiency of the vehicle.