It may seem obvious to some, but there's so much time to be made from taking the correct racing line. This is: Wide in, hit the apex, wide out, effectively turning in as shallow a curve as possible. It's important to slow down before you reach the corner, to ensure you can accelerate through it.
Our video shows how it's done and how it can hand you at least a couple of extra positions each race (note - slow-motion used at times, the game isn't that slow).
If you should overshoot a corner, the most important thing to remember is that the car will not turn under braking. So pump the brakes rapidly while holding the direction you want to go, checking each time to see whether the car has got sufficient bite to make it around the corner.
When involved in a battle with another car, there are other lines you can take. These are:
'Slow in, fast out' is a great tecnique for passing in GTA. Basically, you should approach a corner very wide, slow down a lot so that you can turn sharply, then cut back behind your opponent and take a very late apex.
While they're waiting to accelerate (as they're still turning), you can be on the throttle half a second or so earlier. Just enough to get a run on them down the next straight and hopefully past by the next corner.
The GTA races are chaotic affairs so it's not like you're racing in Gran Turismo and can do this on every corner, but there's no denying it can help, especially in the last lap when the pack has thinned out a lot.
Fast in, slow out:
Basically, all you need to do is get a look down the inside of any slow corner. They'll be forced to brake and take their line, but if you're already on their inside at this point, they'll be turning into a metal wall - you.
While we don't condone using other cars as brakes in the 'smash them up the back end' kind of way, it's inadvisable here anyway if damage is switched on. But go ahead and lean on the side of their car as you turn in, it's just aggressive driving. It works best with slower vehicles like vans or trucks. They might curse you, but all's fair in love, war and GTA.
If your car is slightly damaged and you're in danger of being passed, you can try forcing your rival into an error. This involves letting them get alongside you on your outside, then braking BEFORE them, not after. Just make sure you stop in time to find the inside of that corner and stick to it. Chances are they'll be so glad to fly past you that they'll push their luck on the brakes. And seeing as they're already closer to the outside of the corner than you, there's a very good chance that they'll overcook it and wind up in the wall.