Car has bad gas odor after putting gas in car. sometimes going around curves at speeds of 30mph or so you will get a strong smell of gas. this does not happen all the time just randomly. this has been going on for about 3 months. i have checked under car here and there to make sure that there is no signs of gas leaking and nothing. then 1 week ago i was parked with car running where the right side of car was slanted down. i set there for about 15 min. i noticed gas running down the payment. I brought car straight home and put car on ramps trying to set the car up in the same way when it was leaking gas earlier that day. it did not leak. we kept moving the car in different slopes and could not get it to leak. i had about a 1/2 tank of gas in car when it did leak, but i cant get it to leak now. there does not seem to be a hole in my tank and i cant seem to get the car to leak gas.

see if this link can help you out.
smell gas in and around 2010 mazda 3 Google Search

first if the cap was going bad there would be a check engine light on, system is pressurized, unless you have a check engine light, it may because you over fill it

The number 1 root cause for poor fuel economy is a vehicle running to rich, whether it be through a fouled spark plug, faulty ingintion coil, O2 sensor not functioning properly, and even through dirty injectors. I'd start by first inspecting your plugs and replacing them if its been a significant while since they've been changed. Standard heat index plugs normally last around 50k miles, newer specialty plugs like irridium electrodes generally last twice that. Sometimes you can easily check for bad ignition coils by first smelling them. If the winding is bad you'll have a strong burnt electrical odor, you can also visually inspect for any oil around boot from a bad gasket. That could potentially short one out. I would smell the exhaust to see if it is running rich (strong gas odor) that is an indication that one of my suggestions are at fault. If you have a d.o.t emissions testing facility nearby they can measure exhaust vapors for excessive hydrocarbon output too as well as for any trouble codes that may be in your system (Tn does for a $10 fee) I would also try adding a bottle of isoheet and a good fuel injector cleaner additive at least evrery 3rd or 4th fill up. Let me know what how these suggestions work for you and if you have any further questions

have your tires checked for a shifted belt

speedometer cable is bending.

I have a 2002 Impala, and on cold days on the first start of the day had strong fuel smell. I troubleshot the problem to the fuel pressure regulator on the fuel rail was leaking around the seams. I replaced the regulator and have had no problems since. Hope this helps.
Chad

THE CARBON CANISTER IS MOST LIKELY OVERLOADED, REPLACE THE CARBON CANISTER VAPOR TRAP, IT IS NEAR THE FUEL TANK.

I had an old chevy truck that was carbureted with a mechanical fuel pump. I drove for months with the same fuel smell. It ended up being a small hole in the pump itself, on the side of the engine. It evaporated too quickly from the hot engine temperature to catch. hope maybe that might help if you have a mechanical pump.

The 93-94-95 all have this problem ..the fuel line that come into the back do split and leak ..other problem is with vaccum lines coming off the back of intake and vacuum lines come apart from a 3 way fitting.located fire wall .when these are off will cause gas smell and bad millage .... hopes this helps...

Hi,
May I suggest a locking gas cap. You could put a large piece of cardboard under your car and if there are any drops the next morning that smell like gasoline you might find the leak if there is one.
Cheers,
Ken