Sounds like your friends are passing the horrific germs on to you. They are sick, you are healthy, they pass the germs to you, they get well, you get the world's worst cold. If I was you, pass those germs back to them. The cold is always ten times worse when you get a relapse.
And you need to clean your windshield every time you gas up your vehicle. In addition, check the tyre pressure, check the oil and also check all the fluids.