Leveling up unlocks new mods for your racer. The mods mix around the stats to increase stuff like acceleration, speed, handling, etc, typically at the expense of some other stat. As for tips on A races: Try to chain boosts as much as you possibly can, and never, ever even scrape a wall much less plow into one. Walls reduce your speed a ton, even if you're just grazing them once in a while. Try to: Maximize the number of flips you can do off certain drops & ledges (more flips typically means more speed from the resulting boost) Get transform boosts (by flipping when you're transforming, like into a boat or plane ) Hit all possible booster pads Make sure to detonate the Hot Rod item before it overheats and slows you down Always always always try to get the highest drift bonus possible, and without sliding against walls! Don't forget to max out your start boost, the details of which are discussed higher up in the thread. Don't forget to attack your opponents when you're in All-Star mode. Every all-star attack is different, make sure you know how yours works, and use it right. These can be game changers. Beyond that, you might actually find some of the slower vehicles perform better in A races than the fastest ones because they'll typically have much better handling (which is great for keeping you from plowing into shit) and acceleration (which helps recover from item attacks and wall/scenery collisions). If you're good at staying boosted (without hitting walls and stuff) for most of the race, you can also focus on vehicles with a high Boost stat, but I haven't relied on that stat too much, as a balance of acceleration/handling and speed have seemed to outweigh any of the other combos I've tried thus far -- at least with my driving style. And finally, sometimes it comes down to just finding that key vehicle that works best on any one map, without a bunch of fiddling with vehicle mods and unlocks -- such as specifically using an acceleration vehicle on those maps I haven't completely memorized (or have a feel for), where I seem to do nothing but grind against walls and barriers all day.