I remember those things from when I was still reading comic books -- seems like that's where I saw most of the ads like that. I'm guessing that the targets for those things were people like my maternal grandfather who didn't finish high school and didn't have much scientific understanding. I will give him credit for not buying stuff like that, but it might have been because he didn't have enough money to buy it.
Yes - basically, the charlatans who sold this stuff played on people's desire to have something unique and on the suspicions that some people harbour that big companies are always trying to cheat them.
The key thing I was taught was to try to examine the motivation of individuals and organizations when they are advertising things. Obviously, every organization (i.e. company) strives to make as much money as possible - but for car (and motorcycle) manufacturers, that invariably means trying to build the best (i.e. fastest, quickest, best handling, coolest looking and safest) vehicles they can for a price that consumers can afford - all while being compliant with government regulations.
None of that suggests that car or motorcycle companies
"hide" horsepower or purposely
increase fuel consumption - and similarly, no car company would ever
set-out to build a car that is unsafe.
Now, several companies
have built cars that later proved to be unsafe (
c'mon down GM 1960-64 Corvair and Ford Pinto) - but that was not the goal of the endeavour. Those cases were the results of trying to meet a cost goal or a design target combined with stupid corporate leadership and inadequate testing and government oversight (
sort of like the recent Boeing 737-8 MAX fiasco where Boeing was allowed to sign-off on its own safety certifications - what total idiocy).
Companies simply don't make poor products on purpose - because that would defeat their basic business goal which is to beat the competition and sell as many cars/bikes/vans/whatever....as possible. Fortunately, most people (including your grandfather - and mine - who didn't have much education either) were too wise to buy into those conspiracy theories. My grandpa taught me to look beyond the adverts and examine motivations. Once you understand the motivations of people and companies, most conspiracy theories fall apart.
Anyhow - it is fun to read those adverts and watch the twits on late night TV trying flog this rubbish.
Pete