stepless variable drive

例句：

1. 1.The car has a stepless variable drive, which makes it very smooth and efficient.
   这辆车有无级变速驱动，使得它非常平滑且高效。
2. 2.The new model of the car uses a stepless variable drive to improve fuel efficiency.
   这款汽车的新型号使用了无级变速驱动来提高燃油效率。
3. 3.The driver used a stepless variable drive to accelerate smoothly through the city traffic.
   司机使用无级变速驱动在城市交通中平稳加速。