If you drive a car made in the last decade, it probably has a remote key fob with an encrypted chip to prevent car theft. However, if you drive an older Honda or Toyota that was made in the 80s and up to the early 2000s, your car’s key could unlock more than just your own car.

Your old Honda or Toyota key can gain access to an unlikely place

If you drive an older Honda or Toyota, then there is a chance that you can use your own to unlock other people’s cars. Not just any car, of course, but a car of the same model, year, and make. Vice reported an example of this happening.

According to a story they published in 2017, Joanne Fluegel, a 24-year-old driver of a 2005 Toyota Echo, accidentally entered someone else’s Echo with her own key. Fluegel was leaving a music festival when she mistook the Echo for her own.

She gained entry into the stranger’s car by simply using her own key, only to realize that the car was not hers. She came to this conclusion after trying to turn the ignition, but the car wouldn’t start.

“I went to pull out the owner’s manual and actually looked around and thought, oh my god, this doesn’t look like my car,” she told Vice. “Like, my car doesn’t have a cover like that. My car doesn’t have a baby seat. Holy crap, this isn’t my car.”

She put everything back in its place and posted on Facebook explaining what happened in hopes the owner would see it and know they weren’t robbed.

Older car keys are not completely unique

It turns out that car keys aren’t completely unique. According to Vice, “Honda, for example, only has about 3,500 different lock combinations. That means it’s possible, although quite unlikely that someone else could unlock your door with their key and vice-versa.”

Of course, neither Honda nor Toyota want their customers to live in fear of their cars being easily stolen with a key. Instead, this blunder is largely due to a manufacturing cost issue. It costs money to produce more keys and matching ignition and door key cylinders for the thousands of cars that Toyota and Honda produce.

As such, there are only a finite number of keys and matching cylinders so some cars may have key twins.

Why did the key only unlock the car and not start it?

The reason Fluegel’s key didn’t start the car comes down to the manufacturing costs. The car door, trunk, and glove box cylinders don’t use the same tumblers as the ignition cylinder so it won’t start.

Vice reached out to Toyota at one point, and the spokesperson said they were unaware of this situation. Their response went as follows: “The 2005 Toyota Echo complies with all of the relevant regulatory standards for keys, and these keys exceed the number of mandatory unique combinations. As is the case with most brands and models, if a door lock has been damaged, it is possible that the door may no longer lock properly.”

Fortunately, not many early 2000s Toyota or Honda owners know about this key blunder. So if you own one, just make sure not to tell anyone about it.