Do you have your eye on a particular car? At a McLaren dealer, or independent dealer?
I bought my car from an independent dealer. Before the purchase, I floated the VIN around, and a good Samaritan on this forum checked the VIN with his dealer -- who said it was a good car. Indeed it was a good car, no prior engine or transm. issues.
But b/c I was buying from an Indy, I suspected there would be hidden error-codes. And sure enough, there were! It would take appr. 150 miles for them to light, so I had no idea after my test drive. Long story, short, got everything sorted at McL Houston and nothing serious; these cars just have to be sorted and serviced correctly. For example, wrong antifreeze used at indy. One code error was faulty/malfunction CATS. Free replacement due to federal law, but I suspect indy just wanted to avoid the issue. Bottom line: You may face a serious, hidden issue from any car (Ferrari, Lambo, McL, etc.), but try to check the VIN, and if you buy from an Indy, plan on a quick service at a McL dealer to double check for any issues.
I took more risk going with the Indy, but it was the color combo I wanted. If I had to do over, I would hope for a dealer car with a warranty, just for additional peace of mind.
I did spend an extra 5k on issues, but no matter, my car is great !