How can I calculate the efficiency of an air-powered car?

An air-powered car is powered using high pressure compressed air stored in a tank. The pressurized tank is connected to an air-powered engine. The volume of the tank is 0.3 m3, and the initial temperature and pressure of air inside the tank is 20°C and 30 MPa, respectively. What is the efficiency of the car?

I feel like this problem is missing some relevant information. Efficiency is the ratio of work done to heat provided. None of that information is given; there is no information on the engine itself, its process, or any work done.

Am I misunderstanding this question?

Like you, I have problems with this question. The first is that $efficiency$ is usually defined for a cyclic process in which the working substance is returned to its initial state. You don't have information about how the cycle is completed, so you can't calculate this efficiency (which would be less than 100%).