有三种答案供你参考：
we decide not to buy a car,because the motor vehicle prices is rising.（初中水平）
becuase of the rising motor vehicle prices,we have decided not to buy a car.
As a result of rising motor vehicle prices,we have decided not to buy a car.(高中水平）
至于大学水平,还不如高中的,完全退步了,学英语时间少了