does cg have a guarantee for cars pkurchased

You didn't buy the vehicle from Cargurus. Cargurus is an advertising site only. Similar to Craigslist, Facebook Marketplace, etc. On a ten year old vehicle I'm sure you bought it as is. Most States have a cooling off period law for major purchases such as a house or vehicle. If you change your mind about the purchase for any reason, within a certain time period, you can return the vehicle and get a refund. In my State it's 3 days. Check with your local Office of Consumer Affairs. Hope that helps! Jim