What is allowed in or with the car: questions and answers

For a vehicle hauled by motor vehicle, 49 CFR 173.220 allows more than 500 milliliters of flammable liquid to remain if the tank is securely closed. The tighter drain line is the baseline when that exception does not apply. A quarter-tank slogan is a carrier habit, not that federal highway rule. Ask the carrier what they want so the car can be driven on and off, and follow their written instruction when it is tighter. Close the cap. Do not publish their number as the law. Diesel in a self-propelled vehicle has its own exception in that section if the cap is closed and the tank has room to expand.

Less than on a highway trailer. 49 CFR 176.905 says that for a flammable-liquid-powered vehicle, the tank may not be more than one-fourth full, and the flammable liquid must not exceed 250 liters, unless the Associate Administrator approves otherwise. A full tank that is allowed on a truck can be refused at a port. Alaska Marine Lines tells its customers to deliver the vehicle with less than one-fourth of a tank and calls that a Coast Guard rule. Follow the ocean carrier's written fuel instruction for Hawaii, Alaska, or Puerto Rico.

Yes, unless the carrier's written instructions say to disconnect it. 49 CFR 173.220 says batteries must be securely installed, wet batteries must be fastened upright, and batteries must be protected against a dangerous evolution of heat, short circuits, damage to the terminals, and leakage. Removing a battery and shipping it loose is a different package, not a driveway shortcut. If an alarm will chirp for days, ask the carrier before you disconnect anything. On a ship, 49 CFR 176.905 also requires installed batteries to be protected from damage, short circuit, and accidental activation.

No. A battery that is damaged, leaking, or likely to heat or short is not an ordinary car on a trailer. Follow that model's manual. Under 49 CFR 176.905, a vehicle showing signs of leakage or an electrical fault may not be transported by vessel. Several ocean lines have also suspended electric vehicles and plug-in hybrids on their own ships. Matson has said so. TOTE Maritime Alaska and TOTE Maritime Puerto Rico stopped accepting them effective 1 August 2025. A highway carrier may refuse a damaged pack too. Tell them before dispatch.

Do not pack alcohol as a way around a ban. Inside the car, items stay only if that carrier's contract allows them. A carrier can refuse alcohol. Extra flammable liquid, beyond the vehicle's own closed tank, is a hazardous-materials question under 49 CFR 173.220, not a trunk hack. If the contract is silent, leave the bottles out. State alcohol rules for a package shipper are a different business. Check that state's alcohol agency if you are shipping bottles, not a car.

No. Do not add spare cans of gasoline to get around a fuel rule or to "have enough at delivery." The highway exception in 49 CFR 173.220 is about fuel remaining in the vehicle's own securely closed tank, not about loose containers in the trunk. Other hazardous materials in the vehicle have to be packaged under that subchapter. A carrier can refuse the load. On a ship, the one-fourth tank limit in 49 CFR 176.905 is the vessel rule. Take the cans out. There is no workaround on this page.

Plan on a refusal until a carrier accepts it in writing. Oil, coolant, or fuel on the ground is a fact to report before dispatch. A leak can turn a running car into a refused load. On a vessel, 49 CFR 176.905 says a vehicle showing signs of leakage may not be transported. Fix the leak or tell the company and ask whether they will still load it. Do not wipe the spot and hope the driver misses it. If the car also will not roll, say that too. It is a second problem, not the same one.

The practical instructions: fuel level they will accept, alarms, personal items, and whether the car must roll, steer, and brake. Federal rules are the floor. A carrier can ask for tighter fuel, an empty trunk, or a car that drives on and off. If the prep sheet and the contract disagree, ask the company you booked, in writing, which one controls. RideShipper's checklist is a reminder. It is not their sheet. Read theirs a day before pickup, not in the street while the driver waits.

No. The highway exception in 49 CFR 173.220 is for transportation by motor vehicle. Vessel shipments point to 49 CFR 176.905, including the one-fourth fuel limit for flammable liquid and a ban on loading a leaking vehicle. A full tank that is legal on a trailer can be refused at a port. Electric cars add another stop: Matson has suspended EVs and plug-in hybrids, and other lines have published their own refusals. Read the operator you will actually use. A highway quote does not buy the voyage and does not waive the ship's fuel rule.