Hai,
Yourself and the user could have been going down a hill.
- If you were going down a hill, sometimes they can go a little bit faster.
If in any doubt, you were going at 110Km/h and they overtook you, most likely could be speed-hacking but doesn't necessarily means they are.
Also, if you were on the "ARCADE" Server, there is no speed limiter.
Very hard to judge without any video / evidence links.
Hope that helps,
JamesS014
TruckersMP Patreon.