Velocity by Chris Wooding

A story of reckless ambition, unshakable friendship and the perils of fame, set in a broken future... Cassica and Shiara have grown up in an outback settlement far from anywhere. Life's hard where they live, but these two girls have a dream. The biggest sport on the planet is The Free Race, a dangerous off-road rally in which competitors drive souped-up racers through the badlands. Cassica is a talented driver; Shiara her engineer and navigator. Their mission: to win the ultimate race, a course called the Widowmaker, a three-day rally through the most dangerous stretch of the badlands. Pursuing them will be the Wreckers, a colourful bunch of psychopaths driving monstrous armoured vehicles, hell-bent on destroying any racers they catch. The winners are crowned champions of The Free Race. The losers don't survive. . .