system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5:How does my car know it's actual speed in a slippery condition when the wheels are spinnging?

So I realize my base assumptions are incorrect as I originally thought the rotation of the wheels determined the speed the speedometer read out. I was driving in snow up a hill and my wheels began to spin, rpm went into the 7000's yet I was still only doing 35-40km/h. I just wonder what the mechanism is behind keeping the speed read out accurate while the wheels do what they do. What's happening?
gpt
Modern motor vehicles have a speed sensor on each wheel. It uses the data from each wheel to determine which wheels are gripping the road, which wheels are spinning, and which wheels are locked when braking. 

If your front tires are spinning, the computer would only use data from the rear wheels to determine your speed.