My car started losing fuel all over the highway

Ruptured tank, or one of the components of the EVAP system failed/ruptured. The check engine light indicates you have one or more trouble codes set, knowing that code would likely tell you where problem is. It obviously wouldn't be the fuel line to the engine or fuel filter or you would have lost fuel pressure on highway. All you can do is tow it in and get it repaired. If you plan on DIY, get the code read - buy or borrow an OBDII scanner, since car can't move. Get ahold of an EVAP diagram for your car. Expect to drop the gas tank, this sort of job can be done with basic tools, but you will need a floor jack, jackstands or ramps, and eye protection cuz you'll be up under the car.

Yep,because if you had a loose fitting the gas smell would be overwhelming , your tank is very accessible, all the access is done from the trunk via a hatch cover under the carpet . If the tank is ruptured than every time you start the engine the tank gets partially pressurized and that causes a small hole to become a faucet ... I suspect if you open the gas cap it should minimize the flow rate through the rupture (you will get a CEL but it may be the difference between being stranded) The car should still run so put enough fuel in it to observe where the leak is (gas cap good and tight) If you identify where the leak is coming from then put enough gas in the car with the cap loose and a good automotive welding shop can weld it after the put either water or inert gas (probably Argon) in the tank to prevent an explosion. BTW, most insurance companies will pay for a tow to the repair facility (providing you have road assistance)