Vehicle Purchases are one of the USG Restricted Goods but we pulled them out into their own section here because they are so popular.
If you are going to buy a vehicle with US Government money, you need prior (i.e. before you make the purchase), written approval from the donor.
CRS generally buys vehicles with other donations, not USG money, but if you are making, approving, or executing a request to purchase a vehicle, you should make sure you know where the money is coming from.