Hertz rent a car carbon monoxide leak

I rented a car from Hertz and we drove from Washigton D.C. to New York, while driving we noticed a strange smell but we rolled down the windows and it was fine... later on when the windows were rolled up, my girlfriend and I started getting a headache, and she felt dizzy... She eventually fell asleep(which is Highly unusual for her to fall asleep during the day), and I noticed that I was dizzy too, I rolled down the windows and got some fresh air, but later on when my girlfriend had woken up she was telling me which directions to take, I felt very confused and couldn't concentrate on what she was saying or where we were going... Today I went to the hospital to get checked out and they noted that I was exposed to carbon monoxide... We believe the Car had a leak... do we have any legal grounds to sue? or to get a refund for the rental? Please help

You would yes--at least for testing of your health and any follow up care you may need.