U have a great car. Driving each car is different. If we have the same app then there is a setting called "Vibrations" turn it on. It will help u feel ur car out a lil better. The above responder stated that u should "start" in second gear. In the app its not possible to switch gears before the lil chick drops the flag, so here is what u do...
1.) When starting, rev your engine to the point where the tachometer (Shift light) turns green. Hold it there until the race starts, u will start off with an extra boost.
2.) With the Koenigsegg Agera R, as soon as u "Go!" off the starting line, immediately shift up to 3rd gear. This will give u an additional boost, as the engine RPM'swill match better with the higher gear. (Note: Better tires, and a lighter weight car give u better grip at all shift points, thus, better acceleration).
3.) After shifting to 3rd gear, allow the RPM gage "catch up" and wait for the tachometer to light up in blue (Good shift). As soon as u shift into 4th gear, Hit the Nitrous. This is the final boost to your engine in the acceleration, and it will push u to ur max speed faster.
4.) After you hit the nitrous in 4th gear, try to perfect shift the rest of the way to 7th gear. It will help with the acceleration of the car as well.
Summary: Let the gear shifting attribute to the acceleration of the car in the initial launch as it will allow for the nitrous to act as a secondary booster toward the middle of the drag strip allowing the car to push to its max speed at a much faster rate than it would if used in the beginning of the race.
Good luck. Hope this helps.