The circuit race event is the most common type of combat racing event in the Kras City Grand Championship, featured in Jak X: Combat Racing. It is a lap-based competition wherein you will race against five other racers (varies in exhibition mode) to complete a certain number of laps (anywhere from one to five, depending on the race track).
From the start of the race you may focus on a number of different strategies depending on the capabilities and specialties of your race car. If you wish to immediately establish dominance, you will need a vehicle primarily proficient in the gearbox statistic, but also the engine. With a high gearbox you can jump to speed immediately, then with a high engine you will likely maintain the lead. Next, it is important to grab red eco pick-ups as soon as possible, as you will soon find yourself the target of those behind you.
Once you are in a comfortable lead, it is suggested to deploy any other red eco weapons already acquired upon approaching another red pick-up, so as to have a higher rate of defensive damage against other racers while increasing your chances of acquiring a shield system, the only weapon capable of protecting you from the Peace Maker, and a great defense against other weapons like the tracking missiles. Use your own judgment, however, as the value of certain red pick-ups depends on the situation (for example, the circuit race-exclusive smoke screen is most useful at sharp corners but pales in comparison to the saucer drone on long stretches of road).
If you lack confidence in your vehicle's ability to stay ahead and survive, another strategy is to patiently establish advantageous combat tactics and plan to pull ahead toward the end of the race. Sit back and pick racers off with an array of useful weapons, some exclusive to the circuit race event (namely the Peace Maker and Super Nova). Blue eco pick-ups, which charge your turbo meter, will become a mainstay when using this tactic, both to confidently get ahead to win the race at the end and also to hunt targets down who may be faster than you.
More importantly, however, you will want to go after yellow eco to pose a threat to others to begin with. If you acquire a weapon you don't think will be particularly useful, don't be afraid to waste it to increase your chances of acquiring something better upon approaching another pick-up. Your best bets will be the tracking missiles, Vulcan Fury, and, especially, either the Peace Maker or Super Nova. The former two will help mid-race, while the latter two will help toward the end, as they can immediately take out at least the person in first place, if not every other racer between you and him (mainly the Nova's forte, though the dark eco version of the Peace Maker is capable of this as well).
Also note that this strategy is perhaps the easier of the two, due to the behaviors of the game's computer racers. When you are ahead, as with the defensive strategy, the racers can zoom ahead just enough to keep it competitive, and can even overtake you in some situations. Additionally, some obstacles that apply to you don't to them. On the other hand, with the offensive strategy the computer will still do what it needs to keep it competitive, but instead of speeding up will slow down slightly. It is very rare that you will be drastically out-raced if you don't scuttle yourself. In either case, use your own judgment and consider carefully your vehicle of choice.