24 gallon is intended for Fuel Cells or aftermarket fueling systems. Having a stock, OEM fuel tank that is larger than 24gal is AOK.
Was privy to this discussion previously when there were accusations that someone had swapped in a factory diesel OEM tank into their BMW something-or-other. The conversation was met with a bunch of "meh" shrugs. When the horse was continually kicked, there was lots of ridicule placed on the Mr. Tattletale.
When this was later brought up yet again around said team, and it was confirmed that there indeed was NO such swap, the discussion continued and in addition to a bunch of "So What"s it continued to, "And I mean even if they did, good for them. It's an OEM tank. WhatAreWeGonnaDo? You want to shop around for cars that have a 30gallon OEM tank and it's the tank that was spec'd for the car when it rolled out of the factory, more power to you. I'm sure having that additional 8 gallons means they are 'Totally Gonna Dominate.' Ya know, people need to just worry about their own shit and quit bitching about other people's shit."
I later donned the shoe and kicked at the horse myself when there weren't so many spectators, and there was more clarification but this time from a man in a dress, "Dude, dude, look, look, I mean, if that's the tank that came in the car from the factory then it's fine. That's fine. That's ok. If they want to go swap a diesel tank into a car that came with a factory gas motor, then that's not fine. Because there are different strap hangars, sometimes the floor pressings are different, the frame rails are notched, I mean whatever. Ok? Ok? I mean, dude, if you want to swap a gas motor into a car that was a factory diesel and keep the diesel tank, that's fine. But dude, now we're talking fuel pumps, fuel lines, all kids of shit that I gotta look at. But if it's the stock tank in the car, and it came in that chassis, and it's got some huge capacity, and it's not someone putting a crown vic on some frame rails from an F250 with factory dual tanks, and all the other shit is right, then it's fine. It's fine. But if you start welding in return lines to the tank, or then need to get inside of the tank and swap out the pump or some other shit, then it's not fine. It's not stock. BMW did NOT put a high pressure gas fuel pump with a return line in their diesel cars. They just didn't do that. THAT'S not OEM, so technically that's not allowed. But if they want to try and run their gas motor with a diesel pump, go right ahead. It's not gonna work.. I mean, it'll work for a little while... I gotta see it. I gotta talk to the guys. OEM is OEM, and that shit is fine, but if they start modifying shit, then I gotta see it. I gotta see it."