Can more playable characters be unlocked in Mario Kart 7?

I've collected over 500 coins so far and the only things unlocked from those were new kart customizations. I have also beaten every Grand Prix in 50cc with 3 stars (first time, no less!) but nothing got unlocked there.

There are some regular characters missing from the line-up (like my favourite, Wario) so I assume more can be unlocked at some point. How do you achieve this?

Solution 1:

Here's the unlockable character list from GameFAQS.com:

Unlockable  How to Unlock
=========================
Daisy       1st in Mushroom Cup 150cc
Honey Queen 1st in Banana Cup 150cc
Lakitu      1st in Lightning Cup 150cc
Metal Mario 1st in Special Cup 150cc
Mii         Place 1st in all cups in one CC level.
Rosalina    1st in Star Cup 150cc
Shy Guy     1st in Shell Cup 150cc
Wario       1st in Flower Cup 150cc
Wiggler     1st in Leaf Cup 150cc