there is a gas smell coming from my car when i drive stops when parked

What is your question?

the problem occur when i start the car let it run and drive to my destination, it smells when i get our of the car, after parked it does not smell. There is not a leak as far as i can tell this happened after I took it to the shop when the car messaged me say check air bag they could not find the problem, then when i was getting ready to leave they stated that there was a small leak in evac or bvac and wanted to charge me 400.00 dollars to fix it. when they put it on the machine they did not find anything

What makes this problem better or worse?

only when I drive it, gas is not leaking anywhere just fumes

How long has your 2007 Pontiac G5 had this problem?

Its been about 3 weeks