You just ask to change your post, or resign if you can't. This is only verbal, and you can totally deny it. According to Article 37 of the Labor Contract Law, resignation requires a written notice to the employer 30 days in advance. If you don't resign in writing, the employer will have no evidence to prove that you applied for resignation. Then it is illegal for the unit to dismiss you. According to Article 87 of the Labor Contract Law, illegal dismissal requires you to pay double economic compensation, that is, you can pay two months' salary for one year, and you can ask for two months' salary as compensation for half a year or less.
As for the cost of learning the car, it is estimated that you can't get it back, because you learned the car by yourself, but your learning car is required by your unit, so asking for leave doesn't count. It should be counted as engineering vehicles and working hours, which means that your unit may not deduct your salary.
4. If negotiation fails, you can apply to the Labor Bureau for labor arbitration.