I was browsing some tips over at Charity Navigator and I found this one that I thought was very important:

Find a Charity That Directly Accepts Car Donations
If at all possible, avoid the for-profit intermediary organizations that advertise so pervasively to handle your car donations. When you work with one of these organizations, they keep the vast majority of the dollars created from your donation. Even the most reputable of the agencies that handle these transactions keep nearly 50% of the car’s value for their troubles (other, less scrupulous entities keep 90%, or even more). If you can find a charity that handles the transaction themselves, they can keep 100% of their profits. It’s possible that the charities you already support have a car-donation program that you don’t know about. Check with them first.

If your charity wants someone to start a charity car program you should definitely use a company that give you 100% of the proceeds like ours does.