Park the car and let the engine run for few minutes. See if there's any fluid on the ground. If you don't see anything, then it could just be a spilled gas somewhere. I'd strongly advice you to take the car in for testing. They shouldn't charge you anything for that.
You can take your car to any shop. Pet Shop boys come to mind. You should be able to get a free esitmate on what the problem is. Don't take their word for it though, get 2-3 different estimates. Don't forget your car dealer's service department. They are good for finding out what's wrong without paying first.
