The "Top Driver" awards are as follows:
Best Wrecker - Most damage overall to opponents.
Blast Master - Deaing various types of damage to opponents.
Bulldozer - Ramming into the most track objects.
Fastest Lap - Getting the fastest lap time.
This can come through natural play, but a surefire way to get it is the following.
Enter the "Extras" section of the main menu and type in WOTKINS in the cheat code area. This unlocks the Flatmobile. Start a Bonus event on Figure of Eight 1 and set the laps to one or two. At the beginning just ram your opponents as much as possible and hit as many of the tyres lining the turns. When you're satisfied, head for the finish line. The Flatmobile is so fast, you shouldn't have a problem winning. If at the end your name is under every award, the achievement is yours.