Hot Wheels standard cars (that you would find at Walmart, Target, etc. are made of plastic and diecast metal which is a mixture of metals and this class of metal is stated to be waterproof but does that mean that Hot Wheels themselves are?
Hot Wheels are waterproof in that you can leave them submerged in water and then take them out again without any short term issues. However, since there is metal on them if you keep them in water long term they will eventually start to rust and become damaged.
Another thing that affects whether specific Hot Wheel cars are waterproof or not is that there are many different types of Hot Wheels that are sold and also many different model variations and styles which can also affect how they hold it in water .
Ultimately no Hot Wheel vehicles should be left sitting in water long term as it will cause the vehicle to begin to decay.
Hot Wheels does make more than standard diecast toy cars and this is where the answer to this question can vary a lot.
Hot Wheels original cars are commissioned to be waterproof but what about the axle for the wheels?
Hot Wheels after all were designed for children so being waterproof would be a logical step. All components of the cars are of metal, plastic and sometimes rubber.
Not all Hot Wheels cars made are diecast therefore the answer is open ended that some versions are more waterproof, and some are not at all.
Mattel Hot Wheels Diecast Version
The standard Mattel Hot Wheels are made of diecast metal and plastic. Diecast metal is a mixture of alloy metals and diecast is the process in manufacturing.
The manufacturing of die casting is melting metal down in the liquid form and pouring it into a mold. As the metal cools it takes the form of the mold.
This process is done for the outer shells of the car and the “engine block” which would consist of the base of the car. The remainder of the car would be plastic, paint and decals.
All components are going to be determined by the cost. The tires are plastic along with the “glass” for the windows and the detail associated with the interior of the car.
Axles on a Hot Wheel toy car are made from piano wire. Piano wire will rust when submerged for long periods of time in water. This would be the only component of the Hot Wheels that will not be waterproof and will rust.
You will also likely have decals and paint be damaged from long term exposure.
Mattel Hot Wheels ID Cars
Hot Wheels ID cars are like a standard Hot Wheels car in regards to the outer shell, but the bottom portion of the car has many differences. These cars have technology installed in them on the bottom portion of the car.
These cars have NFC technology installed in them which is Near-Field Communication. It has a chip placed on the bottom covered that is then covered by plastic. This would be the portion of the car that would be affected by water.
Since these cars are designed like the standard cars the components such as the axle will be the same so that part will rust. The ID cars should not be submerged in water and if they are they are unlikely to be able to operate as designed.
Over time the water may break down the components but if you get them wet temporarily it might not get damaged too badly.
Mattel Hot Wheels AI Smart Cars
Mattel Hot Wheels AI smart cars are not made of the same die-cast material that the other Hot Wheels cars are made from and the outer shell is made of a vinyl material.
The car itself is actually an R/C powered vehicle so the vehicle is electric in nature and water and electricity do not mix. All components of this vehicle are completely different then all the other Hot Wheels that they offer.
While these Hot Wheels have more advanced technology, with that comes components that are not able to be mixed with water at all.
These Hot Wheel vehicles are designed for indoor play and are not waterproof and you should avoid waterproof at all costs.
Mattel Hot Wheels Monster Trucks
The monster truck version of the Hot Wheels is a larger scale design, but the outer shell still has the die-cast metal which is waterproof. Standard Hot Wheels are a 1:64 scale and the Monster Trucks are a 1:24 scale design.
The frame of the monster truck had to be added and the use of tubes is used to make for a lighter truck for children to play with. The axles use a locker for the lighter weight. These are made of steel components.
The tires are made of shaved plastic and plastic is waterproof, but the axle will rust over time if it is left submerged in water. The frame is tubing made from metal components that are not die-cast so that is going to also rust over time.
The outer shell is die-cast metal so this portion of the truck and the plastic pieces will be waterproof and not rust.
Overall, this Hot Wheels Monster Truck version is not waterproof.
Mattel Hot Wheels All-Terrain Vehicle.
Hot Wheels produced a larger scale All-Terrain Vehicle with a target age group of 2–4-year olds. Due to these vehicles being designed for toddlers they also contain die-cast components.
This All-Terrain Vehicle has a large-scale base of 1:43 due to original Hot Wheels 1:64 having the small choking hazard. The outer shell is the die-cast metal so this part will be waterproof.
This Hot Wheels vehicle has a working suspension to navigate the outdoors as well as any obstacles inside. It has a larger tire design to work better with the suspension and the undercarriage which is plastic appears to be held together with screws and these will rust in water.
The axles are nickel plated and are resistant to corrosion so by drying these components you will help prevent these parts from rusting.
This vehicle is partially waterproof but a good portion of it will rust after just a little bit of time submerged in water.
Conclusion
Mattel Hot Wheels cars come in many forms of designs and types. The original model cars can work on racetracks or for collectible memorabilia.
The standard model of die-cast cars appears to be the most waterproof of all of the current Hot Wheels models but even it should not be left submerged for days or weeks as some parts will rust, decals will peel, and the paint will get damaged.
The main component in several of the smaller scale cars that will rust is the piano wire that is used as the axle. Many consumers are replacing this wire to make the Hot Wheels completely waterproof but again, the paint and decals will fade and start looking damaged.
Mattel Hot Wheels ID cars appear to be waterproof despite having added technology. The technology has a plastic covering which after submerged in water, the vehicle is still able to be scanned but that is only temporary.
If you leave this vehicle submerged it will quickly become a problem.
Hot Wheels newest technology of the AI smart car is not designed the same way and therefore none of the components are waterproof or water resistant either.
The shell is made of plastic so that would be waterproof but that is it.
Lastly are the larger scale monster trucks and all-terrain vehicles being only partially waterproof. Some of the components can rust but it likely will not affect the functionality of the vehicles but will affect the looks severely.