Complete Carnage Mode with all gold.
(this one is the hardest achievement on the game, follow the links at the bottom for some pointers on the trickiest ones
Online Derby Pro
Win 20 ranked online Derbies.
(Here you have to race with a minimum of 4 people, i guess it can be boosted, but can be quite tricky to get matched up
Live to Crash
Wreck 3 or more opponents in the same online race (normal or Head-On).
(set up a room with 3 friends, get them to park sideways at seperate points of the track, then ram them till they explode
Wreck 10 opponents in online races.
(just get into a room with some friends and take turns smashing each other to bits, if youve done the live to crash achievement, youll only have to do it 7 times each
Time trial tip - http://www.xbox360achievements.org/f...ad.php?t=31550
Final beat the bomb tip - http://www.xbox360achievements.org/f...ad.php?t=30862
General game tips - http://www.xbox360achievements.org/f...ad.php?t=30177