Re: buying from PI, PM or 2nd hand
For new cars, start with this route - what car am I getting? Will I be modding?
If no, stick to PML - it gives a sense of comfort in case things go terribly wrong in the first 3 years. That does not mean that service is utmost.
If yes, look around. What are my savings? Who's this PI? Any history, or fly-by-night shop? Who supports them in the after-sale service? Who covers the warranty? For how long?
At the end of the day, PML is far from perfect - we all know that. PIs are not all rascals too. So there is value/savings to be extracted if do your research properly.
For used cars, it is a bit complicated. Valuation in terms of depreciation comes into play, and marque/model history plays a part. Best is to ask around this forum for advices pertaining to certain models.