Is it possible for a car be 100 percent fuel efficient?

It is not currently possible for a car to be 100 percent fuel efficient. Even electric cars, which are often considered to be the most fuel-efficient vehicles, still lose some energy through heat and other inefficiencies. However, some cars can come close to 100 percent fuel efficiency under certain conditions. For example, a hybrid car can use regenerative braking to capture energy that would otherwise be lost when the car brakes, and then use that energy to power the car's electric motor. This can increase the car's overall fuel efficiency. Additionally, some electric cars can also use solar panels to generate electricity from the sun, which can help to extend the car's range. With ongoing research and development, it is possible that in the future we may be able to develop cars that are even more fuel efficient than those available today.