Madagascar Kartz

Easy.
It's important that you choose 150CC as a class! The achievement won't unlock on 50CC, 100CC or 200CC.
Choose "Watering Hole" and then SHREK, cause he is the fastest racer.
2:55.00 --> Bronze
2:45.00 --> Silver
2:35.00 --> Gold
So, you have to beat 2.35min. It's important that you try to drift on every corner. Like that, you will fill up you're boost meter. And use as much boost pads as possible! And do stunts to fill up you're boost. In the "Watering Hole" it's also necessary to boost in the curves. Like that, you will take them sharper and faster. After the jump, go right and don't run into that car, that will drive towards you. He can do some serious damage. Don't jump on the belly of the hippos, stay right and drive through the little river. Avoid the heads of the giraffes, by staying all the way on the left side. You can also drive through the grass, but use the boost, if you do so.
Race the track a couple of times to get a feeling for everything. Shouldn't take too long.
Achievement unlocked!