It is ur fault actually. U should have checked the car b4 signing it. But im not sure about the car u got n what is stated in the form. Logically, the agreement is void if what is stated in agreement is different from what u got. Meaning u drive the car and if anything happens, it will be under ur full responsibility coz the car rental did not give approval for u to use the car.  But u were aware of this, n signed it. So, this is a bit tricky.