Post object instead of string when using trackEvent

I’ve added some tracking code like this in my website:

_paq.push(['trackEvent', 'Car construction', 'Add wheel', wheelId]);

However, I was wondering if it was possible to add more info to this event. Something like this:

_paq.push(['trackEvent', 'Car construction', 'Add wheel', {carName: "Buick", wheelCount: 3, wheelId: wheelId}]);

It’s a made-up example, but the thing is, I want to connect more than one value/property to my event. I’ve seen this in mixpanel, but it isn’t clear from the Piwik docs how/if this is possible. So I’m guessing not, but wanted to be sure.

The last answer in this question says I “may use trackEvent with any number of custom variables.” But I’m confused, as I thought you can only pass in Category, Action, Name and Value in the trackEvent function?