What product do automakers ever suggest to better the car?
I haven't heard of one.
And why would they? The less you take care of your car, the more they profit..unless you know how to wrench your self.
Manufacturers do recommend regular maintenance. While this may not "better" the car it certainly keeps it going for, typically, 10-15 years in the case of modern cars.
By following the proscribed maintenance schedule modern powertrains will easily go 200K+ miles. At which point the rest of the car needs work (body, a/c, interior, axles, transmission, etc.) and the car is probably not worth putting any more money into. So, please, do tell how these miracle products such as Seafoam are going to help with this.
Even without products like Seafoam powertrains outlast the rest of the car in most cases. So what's the real point in a product like Seafoam? I can see none. Unless you're saying Seafom will reduce maintenance costs and if you are I'd love to see real evidence of this.
Manufacturers don't recommend products like Seafoam because there is no need for them. There is no conspiracy here. 30-40 years ago you'd be lucky to get 125K miles out of a powertrain without it needing major and expensive work and yet today we expect and get almost double that. Why would automakers improve reliability so much if they were simply interested in planned obsolescence? I have yet to see any good answer to this question. Likewise with bodies. 30-40 years ago a new car would have an incredibly high amount of body rot after 5-8 years. Today such rot typically doesn't show up on a well maintained car for 10-15 years today. And yet we still have planned obsolescence according to some.