MudRunner

"Repair & Refuel" is the second challenge you will do and goes as follows:

Main Challenge
- Repair and refuel trucks by using other trucks, deliver logs to the Lumber Mill

The main challenge is self explanatory really. Just follow the instructions you receive on the top right corner in the text box and you should be fine.

Bonus objectives

- Scare 10 birds by using your horn
This is an easy one. To sound your horn press . The truck with the logs has the loudest horn, but I managed to get this also with the other trucks in this challenge. Make sure that you are close to trees when using your horn. Remember that as soon as you completed the challenge you will see a short pop-up saying so. No need to count the birds you scared away!

- Don't drive over the bridge
Pressing will show you the map. The most obvious passage is the one right next where you start, but as this is the mentioned bridge, don't take it. Instead drive to the fuel station again and instead of going right, you will see a path that goes through the river. Take that one! Then drive to the Lumber Mill as usual.

- Find and squash a pumpkin
I found this one to be easier done with the "B-131". When you're about to go to the fuel station to fill up gasoline, instead of going to the fuel station, take the path through the river. When you're on the other side, follow the path a little bit until you see a hut at the right of your car and you will notice a field of pumpkins next to this hut. Just squash one and drive back to the main objective and get gasoline.
If you really don't want to loose time, you can still do it on your way to the Lumber Mill, as this is the path without using the bridge. But I found that turning out of the pumpkin garden is a bigger pain with the "C255" truck and the log trailer.

Note 1: You will immediately see, if you failed or achieved a bonus objective as a pop-up text box will appear right under the instruction text box, saying "Bonus objective xy failed/completed"
Note 2: If you fail a bonus objective, the stars you earned will carry over to the next run you do. So let's say you completed already 2 bonus objectives, you only have to complete the last one on your next run.

If you have anything to add that is helpful to this solution, write a comment.