These versions of the 50cc and 100cc which are similar but slower to the 150cc version are unlocked by completing ALL the cups in the indicated CC. To activate these versions you have to press the + button at the 'Speed Select' screen.

Unlock 50cc (Karts and Bikes):
Place 1st, 2nd or 3rd in ALL 50cc cups.

Unlock 100cc (Kart and Bikes):
Place 1st, 2nd or 3rd in ALL 100cc cups.

If you change your drivers weight at the Mii Channel your ingame weight class also changes and you will have a different car.

If you mainly use the wii wheel in ALL the different modes of the game a golden wheel will appear next to your name when you go Online.

This mode becomes an available option when you have won ALL the cups at 150cc class.

Try unlocking these great characters in the game by completing the indicated task.

King Boo:
Win 50cc Star Cup

Diddy Kong:
Complete ALL 50cc Cups

Dry Bones:
Win 100cc Leaf Cup

Mii (Outfit A):
Win 100cc Special Cup

Daisy:
Win 150cc Special Cup

Baby Daisy:
1 Star in ALL 50cc Wii-Cups

Bowser Jr.:
1 Star in ALL 100cc Retro-Cups

Dry Bowser:
1 Star in ALL 150cc Wii-Cups

Funky Kong:
In Time Trials unlock 4 Expert Staff Ghost Data.

Baby Luigi:
In Time Trials unlock 8 Expert Staff Ghost Data.

Birdo.
Play Time Trials on 16 different courses

Toadette:
Play Time Trials on ALL 32 different courses.

Rosalina:
Have a Super Mario Galaxy 'Save' file and she becomes available after some GPs.

These are unlocked when you get at least 3rd place in the correspondng Cup.

Special Cup:
Get at least 3rd place in Star

Lightning Cup:
Get at least 3rd place in Leaf Cup.

Leaf Cup:
Get at least 3rd place in Banana Cup.

Star Cup:
Get at least 3rd place in Flower Cup.

Just complete the indicated task for the Bike you want to unlock in your game.

Quacker (Small Bike):
Win 150cc Star Cup.

Bubble Bike (Small Bike):
Win Mirror Leaf Cup.

Magikruiser (Small Bike):
Play Time Trials on 8 different courses.

Dolphin Dasher (Medium Bike):
Win Mirror Star Cup.

Nitrocycle (Medium Bike):
Get at least 1 Star Rank for ALL 100cc Wii Grand Prix Cups.

Rapide (Medium Bike):
Win 100cc Lightning Cup.

Torpedo (Large Bike):
Unlock 12 Expert Staff Ghost Data in Time Trials.

Phantom (Large Bike):
Win Mirror Special Cup.

Twinkle Star (Large Bike):
Win 100cc Star Cup.

If you want to unlock the following Karts for your game you have to complete the indicated task.

Cheep Charger (Small Kart):
Get at least 1 Star Rank for ALL the 50cc Retro Grand Prix Cups.

Rally Romper (Small Kart):
Unlock 1 Expert Staff Ghost Data in Time Trials

Blue Falcon (Small Kart):
Win Mirror Lightning Cup.

Turbo Blooper (Medium Kart):
Win 50cc Leaf Cup.

Royal Racer (Medium Kart):
Win 150cc Leaf Cup.

Dragonetti (Large Kart):
Win 150cc Lightning Cup.

Piranha Prowler (Large Kart).
Win 50cc Special Cup.