Here is the full list of all 26 Hero Express achievements.
Make 10 frontflips in a single run
Make 10 backflips in a single run
Bring all the M-00-N stats to level 7
Finish every track
Reach the end of the Moon track
Bring all the Flaming Speeder stats to level 7
Reach the end of the Vulcano track
Bring all the Tukie Tuk stats to level 7
Reach the end of the Himalaya track
Reach the end of the Great Wall track
Bring all the Amber Dragon stats to level 7
Reach the end of the Amazon Forest track
Bring all the Transporter 2.0 stats to level 7
Reach the end of the Swamp track
Bring all the Wild Tiger stats to level 7
Bring all the Duner stats to level 7
Reach the end of the Sahara track
Bring all the Undertaker stats to level 7
Reach the end of the Transylvania track
Bring all the Ice Breaker stats to level 7
Reach the end of the Noth Pole track
Bring all the ZEAT stats to level 7
Reach the end of the New York track
Bring all the Kahuna Laguna stats to level 7
Reach the end of the Treasure Island track
Spend 45 seconds in the air in a single run