Game Center achievements...
	Invisible car...

Complete the following tasks to unlock Apple Game Center achievements.

Achievement	How to unlock
Atlantis Arrowheads	Collect all of the arrowheads and win the Atlantis race.
Atlantis Race	Finish an Atlantis Race in 1st place.
Crete Arrowheads	Find all of the arrowheads and win the Crete race.
Crete Race	Finish in 1st Place in a Crete Race.
Desert Arrowheads	Collect all of the arrowheads and win the Desert race.
Desert Race	Finish in 1st Place in a Desert Race.
Giza Arrowheads	Collect all of the arrowheads and win the Giza race.
Giza Race	Finish in 1st Place in a Giza Race.
Glacier Arrowheads	Collect all of the arrowheads and win the Glacier race.
Glacier Race	Finish the Glacier Race in 1st place.
Jungle Arrowheads	Collect all of the arrowheads and win the Jungle race.
Jungle Race	Finish in 1st Place in a Jungle Race.
Medieval Arrowheads	Collect all of the arrowheads and win the Medieval race.
Medieval Race	Finish in 1st Place in a Medieval Race.
The Great Wall Arrowheads	Collect all of the arrowheads and win the Great Wall race.
The Great Wall Race	Finish in 1st Place in a Great Wall Race.
Viking Arrowheads	Collect all of the arrowheads and win the Viking race.
Viking Race	Finish in 1st Place in a Viking Race.

When driving in the desert map, there is a sphinx. Drive under the head and your car will be gone but your shadow will remain. Note: This will only work if you stay under the head.