Rocket League is getting set to do a cross promotion with Euro Truck Simulator 2 however don't expect anything good from this such as a truck to drive. As part of the new promotion Rocket League will be receiving an item in reference to Euro Truck Simulator 2 and vice versa.
As part of the next patch will be getting a Euro Truck Simulator Rig Antenna, and Euro Truck Simulator 2 will soon be getting a Rocket League dashboard toy and a ball as a rear view mirror hang. You can see the images below:
A recent Euro Truck Simulator 2 update means cabin objects now have physics, so your new Rocket League items will be moving around as you drive.