I think I already know the answer but I will ask just to make sure.
Assuming the skill of the driver is constant and the car is upgraded fairly decent. Will tuning vs stock tuning really change that much in terms of lap times? I feel like it’s a tenths of a second kind of change, would I be right?
Driver skill could have seconds of difference when it comes to lap times so clearly this is the most important factor.
It probably isn’t much, but the game is programmed so that your tune slows the Avatar drivers down, so a better tune wins more races based on that. That’s because computers have speed limits, and slowing the Ai down is easier than speeding up the game.
I think the impact of tuning varies pretty heavily based on the ability of the driver. I myself am a good driver…not a great one. Surely not one of the upper echelon in the game.
As such, the ability to tune a car so that it responds to my style of driving is pretty important. I need to feel in control of the car, to have it respond as I need it, in order for me to avoid obstacles and take turns at an acceptable level. For me, this makes the difference of seconds of time in my runs. I can not bang out 10 runs and have them all fall within a second of each other, especially if the car is not responding as I would like. I do most of my own tunes. Some of them are nearly perfect for me…others are disastrous, lol. And some cars as stock, or just upgrading but not “dialed in” are not suitable to me at all.
More importantly than time, although that is the premise of your question, is that having a good tune feels better to drive. It is a more enjoyable experience. So in shaving off tenths of a second or 3 seconds, having a good tune is simply more enjoyable. There are cars I drive around the map completely untuned. Or run in lower level races. This is also fun. But when it comes down to being in a competitive race, I find a tune does make a considerable difference. To me, anyway.
Also reaching the rev limit in top gear is annoying, and I like to fine tune that so that the rev limit keeps going up. For example on a long straight the engine will start to repeat its tone, if you push up the car’s top speed you can time it perfectly to the next bend.
Your question is vague, a ‘tune’ in Forza parlance is usually used to mean the whole upgrade package, which can make a profound difference to the lap times a car can achieve, even within the same class.
Are you asking if a car is upgraded with parts to bring it up to, for example, A800, does it make a difference if you just slap the parts on but then don’t change any other settings, versus changing some? Even then, doing the latter can make a significant difference.
Most normal road cars are designed to have pretty strong understeer. For safety reasons, understeer is stable. But for racing you want to have slight oversteer, that allows you to swing your rear end around sharp corners if you know what you’re doing. Most normal cars also have soft suspension, cause thats comfortable. But you’ll want a hard and low suspension for racing.
Proper upgrading is extremly important. Its necessary for pretty much every car. But upgrading changes the base characteristics of a car. Weight, weight balance, power, height, etc. If you don’t adjust the tuning to the new characteristic of the upgraded car, it will behave awefull.
Adding a rear wing without making drastical changes to the supension will make the car almost undriveable.
So if you start with a propper race car, and it was propperly tunes to begin with, and you don’t make drastical changes to the car, tuning is optional. Otherwise you’ll need to tune. Upgrading is a must have in almost all cases.