Yello mate!
Yes, it is most possibly ending fuel. it is often happening on last corners of last lap, or when someone is doing one extra lap after the race, and have low fuel. It is caused by missynchronized data between player and server. Server 'thinks' that the player have 0 fuel, while actully he/she have about 0,3% (maybe less). So server is sending info to other players that fuel of, let's say 'driver A', is 0 so also his engine can't be turned on, while he actually have tiny amount of fuel left, and is still able to drive.
I don't know the right amounts but let's say that server is refreshing data once per 0.5s. Let's say last refresh was like now, next in 0.5s. The last sent data was that Driver A have 1% fuel, full throttle, 3rd gear and 120km/h (+ a lot of different data), so other players got that data and their PC is calculating how driver A will accelerate (+ much more stuffs) during the time until next refresh. After 0.5s, PC calculated that Driver A speed will be 123km/h, but the next refresh said his speed is 122.5km/h, because he lifted throttle for a bit during that 0.5s. Now other drivers pc will have to compensate that difference, and they will see lilttle "blip" on that car, which we see all the time because of such small corrections.
And now lets say Driver A have 0.1% fuel, full throttle, 3rd gear and 120km/h. But server sent data to others that Driver A have 0% fuel instead of 0.1%, and now their PCs calculated that after 0.5s driver A speed will be 116km/h because even though he had full throttle, he can't accelerate, because he has no fuel. But again, next data that server got from driver A is that his speed is 123km/h, because he actually had 0.1% fuel, so he was able to accelerate. And now there's 7km/h difference and also difference in driven distance during that 0.5s which generates big "jump" of the Driver A car, on screens of other drivers. And it pretty much looks like speed hack, because car of driver A will be jumping like that every 0.5s (but only if he is on throttle), when the server sends new data.
And that's why it looks like that, and may look like cheat, but if you will look closely to that jumping car, it will not get any advantage, or higher speed than others. Just will be "jumping", reducing speed between server refreshes, just to jump few meters ahead and gain speed ON next refresh. I know i didn't described that good, and it might be hard to understand what i mean, but i can't do it better, also all the numbers i used are only examples, it's probably different in reality.
PS. If you see a car jumping like that AND gaining advantage, havig a lot higher speed than others, or making unrealistic times, and all that not only on last lap, but all the time, you probably see a cheater. Also you might notice that some players can accelerate on much higher revs than the car is able. like they're getting 15k rpms on xfg, and after that they didn't lost power, and can still drive fast, that's cheat too.
