The MP4-12C faced teething problems related to electronic glitches and software, and the M840T engine in the 720S had occasional reports of overheating and misfires. It’s important to note that McLaren actively addresses these issues through software updates and continuous improvement. Early version of the M838T also suffered from valve train wear, although this was address on latter engines, but it still affects these earlier versions. Both engine versions have suffered from cylinder liner issues and even con rod failure.