The law in most states in the US does impose two warranties which are relevant here - the warranty of fitness for a particular purpose and the warranty of merchantability. These are warranties that go with the sale of goods regardless of what the manufacturer/dealer may offer, or, typically more significantly, disclaim. These are complicated warranties that apply differently to different types of products. For example, these warranties would impose a longer term of warranty for a car than a toaster - everyone knows and expects a car to run/operate reasonably for several years whereas a toaster may only operate for a year or less. The essence of these two warranties is that the good must be delivered in a condition which is appropriate for the nature of the good and be fit for use in the way that good is normally used. This would mean that, for example, a car should be fit to use as a car, operate in the way cars normally do and should defects show up in a reasonable amount of time (again, appropriate for a car) the seller must repair or otherwise make amends.
So, net, even if there is no stated warranty, you're not totally out of luck and on your own, at least in the eyes of the law in most states. It may require engaging a lawyer to enforce these warranties and bring about an attitude adjustment upon the seller but that's what we have the law for - to provide an equitable outcome where particular behaviour has been unfair.
As is correctly pointed out above, with respect to SPF you would have the above two warranties upon the car with the exception of the drivetrain.