It's important to distinguish between the hacked, modded experience and any official support. "My Summer Car" does not have, and has never had, official multiplayer or co-op functionality. All multiplayer experiences are entirely unofficial, created by fans. This means there are no dedicated servers, no customer support for online issues, and no guarantee that any progress made in a multiplayer session will be stable or permanent.
No, not without mods. The base game is strictly single-player. My Summer Car Cracked Multiplayer