Off to do some XMas shopping, so I'll leave you guys with this info. Unlike other racing sims, the default setups are VERY good. Your very first step should be confirming that you are driving at the absolute limit with the default set. Second step should be installing the performance shaper app to get an iRacing-like live-timing system to see EXACTLY where you need to improve. To gain some extra speed: Your first change should be tire pressure. On a track with many long straights (Vallelunga), bump up the PSI by 2 or 3 all around. On a track with many rhythm sections such as Imola, lower the PSI by 2 or 3. That'll get you more corner grip. The next change should be wing settings. Basically, you want the rear wing as low as possible without causing great amounts of oversteer. Experiment to find the best setting but usually I cut whatever the default wing amount is in half. You'll always want some amount of aero grip on the front end so I leave that setting stock. The exception to this is the Formula Abarth, which responds very well to 16/16 on the wings. My rule of thumb is that if there's giant wings on the car, they're probably there for a reason and you should use them. Fuelwise, most cars in AC begin with 30L, I cut that in half to 15L. Depending on the track, this'll get you anywhere from five to eight laps on a tank of fuel, more than enough to eat up the tires. The tires should be using as soft of a compound as you can. For fast times, anyways. Coast Diff is a simple handling fix; it'll make the car turn-in better by causing lift oversteer when you move the slider to the left. Very handy with the naturally understeering GT2 and GT3 cars. Ideally, you'll want a very SLIGHT amount of oversteer; you'll end up in the sand if you go to 0%, especially in cars like the Lotus 49. Rear camber is another handy fix that helps the car behave better in the corners. A negative value will help the car plant better in corners. Gotta really experiment with these settings but usually the default setup provides nice starting values. On places like Vallelunga with long sweeping corners, you'll want a bit more negative camber in order to get more power down on exit, whereas some of the faster tracks like Mugello don't require much rear camber at all because you're already hauling @$$. For hotlapping, wheel rate should be as low as it can go to stiffen up the suspension. This'll get you more straightline speed. Dropping the ride height a bit helps, too much will cause problems when you start to run over kerbs. Use your own discretion based on the track. Imola has some pretty steep kerbs whereas Vallelunga's are flat. If you see sky going into Tamburello, your car is too low, bro. Gearing, all you really need to adjust is final drive because the default values are quite good. Basically, you want to be around 2-3 mph away from hitting the chip at the end of the longest straightaway in high gear. Unless you're running at somewhere like Vallelunga Club, you won't need to touch the gearing as it's quite good by default for all cars. Brake bias is your final adjustment, and it is relative to the front end of the car (example, the value "70" means 70front/30rear). I rarely touch this, but there are some people who will benefit from it. Too much front bias and you'll loop the car. Too much rear bias and you'll create unnecessary understeer. Be smart and play around with the in-car aids. CTRL+T enables car-specific traction control, and CTRL+A enables ABS. ABS is a godsend. As for TC, you'll want the lowest setting possible for each car. For example, in the case of the Z4 GT3 car, which has 12 levels of TC available, level 1 is pretty much perfect for competitive times. Hope others can add more.