2004 I35. Lately during engine start up or shutoff, I get a strong gas smell in the car, for about 1 minute. No sign of leakage under the car, or in the engine compartment. No check engine light . Any ideas ?

 

You may have a rubber fuel hose that is beginning to harden and crack. When it is cold, it will leak a tiny bit that you may not be able to see as gas evaporates pretty fast. On the passenger side of the engine, there is a hose that connects the ends of the 2 fuel rails together. There is a similar hose on the driver's side.

Another possibility is the connection on top of the gas tank. Remove the rear seat bottom cushion and then remove the round cover in the middle of the floor. The connection for the fuel pump is under there.