It could be also as simple as him pumping the gas, spilling it over the side of the car, and then him touching the inside with gasoline stained fingers. That could also cause the gas smell.
I*m sure the dealer would*ve helped him out. If not, take it to another dealer. Also, this could just be him regretting his purchase and wanting a refund so he can buy a different car.
I have to admit, I test drove the Mazda CX-5 GTR and it did make me feel nauseous compared the other crossovers I*ve been in. I really wanted to love it and I*ve been researching it for months but that one test drive made me look elsewhere.