Robbery done in my car? Police have taken my vehincle?

Ok, so the problem is that a robbery was done in my car and the police now how my vehicle. The story is the my son, daughter and his friend were in my car and apparently my sons friend decided he wanted to steal someone's iPhone 5. My daughter and son told me they were unaware he was going to steal someone's phone, they were driving him home. He asked them to stop and roll around the corner for him one time and stop back in the middle. My son and daughter were both confused so they did it anyways, as they came around the corner my sons friend starts running into the car and yelling at my son to drive. My son drove and then later was told by his friend that he stole a phone. Now the police have my car and they may not give it back. I don't really know what to do.

Any suggestions on how I can get my car back?

Your children allowed a crime to be committed using your car. Are you surprised it is impounded?
You now have to wait until the Police finish with it and then pay the towing and storage fees to get it back
You need to be more careful who you let have your car.

They may have it now to process the vehicle. After a day or two, the vehicle should have been processed and able to be released. The car likely will not be seized because you were not a party to the crime. The vehicle is owned by you.
I would give it a day or two, then call the police and see if the vehicle can be released. I would not wait too long since it will start racking up storage fees.

You will have to pay for the tow and any additional fees related to the tow.

Your car is evidence and was used in a crime. It is treated no differently than the gun taken off the bankrobber. You might get it back eventually, Contact the local DA to discuss it further. BTW, if you are asking if your kids' story of innocence is likely to be believed, it is not.