I bit the bullet and bought the Swift myself : still had to refuel in the 8th-Round. I finished 20 Seconds short of the lead.
After adjusting gears I could push it to the 9th: Still came in too late to make a difference.
Turned down difficulty: still no pit stops by the leader. Placed second again
The real cheat here is that GT does not really tell how fuel mapping works or that it exsists at all if you don´t do the challange attached to it.
Copy-Paste:
First of all, you’re going to need to display all race info . So pause the game, go to Settings, then Display Setting then, under Race Display, set Show Race Info to “Display All”. Now, in the bottom-right corner of the screen, there’s a Track Map. What Sarah didn’t tell you is that you can change what’s displayed in this corner, and even control some of it. Tap left on the D-pad just once, and Track Map will change to Fuel Map.
There are six different Fuel Map settings with 1 being the most powerful, and 6 being the leanest. You can switch between these settings using up and down on the D-pad when the Fuel Map is displayed.
That beeing said, next try is starting with 6 or 5 and blowing the rest of the fuel in the last two Rounds.