Here is the full list of all 20 Slowdrive achievements.
Faster than 3 stars for 1 second
Drive 100km
Get 3 stars on 15 levels
Find 15 leaves
Jump 40 meters
Drive 10km
Drive on two wheels 15 meters
Jump 20 meters
Get 3 stars on any level
Achieve speed 50kmh
Get 3 stars on 30 levels
Get 3 stars on 60 levels
Find 30 leaves
Find 60 leaves
Finish the game
Complete all levels
Get 15 gold wheels
Get 30 gold wheels
Get all gold wheels
Get all ice wheels