What do the colored steering wheel icons signify in multiplayer?

When playing in multiplayer, sometimes I'll notice after a race when it shows points gained/lost, some players will have golden or silver steering wheel icons on their rows.

What do these icons mean?

Toomai and GnomeSlice are right. Those players are using the Wii-wheel.

I'm not sure how long you have to play with it in 8, but someone here said 50 races (You have to win 50 races, not just play 50 races). I'm pretty sure there are three in MKW (white, silver, gold) but I don't know about MK8. I haven't seen any players with a white wheel online yet. I'm pretty sure the icon only shows up when you're currently using tilt controls.

In any case... White players (if they exist in 8) are playing with the wheel but don't have any achievements with it. Silver players have reached the first benchmark (if the cap for gold is 50, this one might be 25 races) and the gold players have reached the final benchmark, if the 50 races is to be believed.

I noticed when I was looking for the number of races you have to win to get the wheel that sometimes people say you have to beat all the ghost data in the time trials for the golden wheel-- That process unlocks the gold tires for cart customization. But the way it's shown in cart customization makes it look like a golden wheel. Just in case you go elsewhere and see someone saying the golden wheel is from the time trials, this is what they're talking about.