What does " Fuel 2/8 start" mean ?

At the counter when pick-up, I was emphasized on non smoking and full fuel return... At the car, I was found it had a slight smell... different from a brand new smell...smoke. And more... the staff showed me the car had fuel 2/8. I gave a question, " Is the same fuel amount return okay?" He said "Yes."...But...it was a difficult mission...2/8 fuel return. In fact, I returned the car with fuel 1/2. If the company urges the driver on the full fuel return, it should fuel up at first. The car pick-up place Don Mueang airport is located in the area without gas station ?