Master Tuner Achievement
Earn 15,000 credits from the community using your tune setups.
For best efficiency, do this at the same time you work on the three design achievements. This is easiest to do with a second profile on your Xbox One, but you can also do it with a group of 15-20 other people where you each commit to a 2-3 week boosting process consuming about 20 minutes a day. This guide is written based on doing this solo with a second profile.
On your main profile you will need to create and share a tuning setup for one of the cars initially given at start of the career. To do this, go to the Career menu, choose Car, and get in the vehicle in question. This will place you back at the Career menu, so choose Car and then Upgrade. If you have previously changed the parts on this vehicle, go set everything back to defaults first. Press to enter the Tune Setup screen. Change the front tire pressure by tapping the once to either side, and then press , choose "Yes" to apply the change. Press the Setup Manager button and choose "Save Setup". The icon at the bottom of the screen should default to an arrow pointing down towards what is presumably a disc drive, so press and enter a unique file name. Press to save the file and the Share menu will appear. Choose two keywords (mandatory, but which ones don't matter) and then any description you wish, then choose "Share". At this point, your tuning setup is able to be downloaded and used by others in the community.
Now switch to your second profile. If you haven't created one on your Xbox One previously, you need an email address to do so, and Microsoft will give you one at no charge if you go to outlook.com. When you are signed in to your second profile you will need to load up Forza 5. Note that if you have never played Forza 5 on the second profile before, you will need to progress slightly in the campaign before it will let you exit to the main menu. When you are selecting your initial vehicle, pick the same car as you chose above on your main profile.
Once you can get to the main menu with your second profile, go to Career, Car, Upgrade, and press the Setup Manager button. Choose "Load Setup" and then press to move to "My Tunes" at the top. Press the search button and under Creator put in your main gamertag and choose "Search". The tuning setup you just created will appear, so press three times to select it and apply it to the car.
From the main Forza screen, choose Multiplayer, press to create a private match and to confirm. Once the vehicle selection screen opens, ensure that the car with the downloaded design is selected. At this point you will be in the lobby. Press to change the options to match these choices:
Game Type: Drag
Track: 2-player 1/4-mile drag
Max Players: 2
Max Drivatars: 1
Drivatar Difficulty: New Racer
Car Class: Any
When you go back to the lobby, press to start the race. If you press as soon as the Post-Race screen appears, it will take approximately 4-5 minutes to complete the 10 heats, at which point you will be back in the lobby. Press to restart the process. You will need to complete a minimum of 100 heats and a maximum of 150 heats on each day. If you complete fewer than 100, you will get credit for zero. If you complete more than 150, you will get credit for 150. The official day for Forza 5 is based on GMT and restarts at midnight. You will need 315 heats to earn all of the tuning achievements.
In game notifications of the credits earned should arrive around 1 am GMT in the Message Center. From the main menu, choose Message Center and press twice. A message titled "Tuning Award" is what you are looking for and will list how much money you made from tuning setups the previous day. Any achievements will unlock upon reading the message.