Error cars are Hot Wheels that have something wrong with them, such as mismatched wheels and missing parts.

One off-shoot of some Hot Wheels collectors are what are considered as "Error Cars". In general, error cars are examples of Hot Wheels with some sort of odd difference that gets by the manufacturer's Quality Control.

There are a lot of different varieties found that can be considered as errors. These would include both vehicle and packaging mistakes. Some of the common vehicle errors are mismatched wheels, missing, broken or loose parts and tampo oddities. Packaging errors include vehicles packaged on the wrong card or blister bubble, cars packaged upside down or turned to the left versus the standard right-facing packaging. What some collectors might see as an "error", if more than one example of the mistake is discovered, others might call it a "Variation".

It's impossible to put a value on these oddities, even though they can be far more rare than any other Hot Wheels found. Error Collectors are a niche that determine the value of each individual example. Since errors can be faked, there's not a big demand for them in the secondary market.