Automotive aerodynamics observations

Here is an automotive rant post that was concocted out of sheer limited knowledge on automotive engineering and basic aerodynamics after a few months-old observation on average Proton saloon cars that roam the roads of Malaysia at an average speed of 60-70km/h.
That, I hope I am not wrong, is a rear spoiler. Serves to increase downward force based on the theory of aerodynamics resistance which, was first observed by smarties like Aristotle and Galileo Galilei and first developed by Isaac Newton.

I was sitting in the back of the car a couple of weeks ago and I couldn't help but notice the craze in young car owners who get rear spoilers assembled on their Proton cars. Rear spoilers cost perhaps a hundred dollars in U.S currency (not too sure, I am no car fan, I prefer to know about automotive aerodynamics than car modifications). Which, is approximately RM300 when converted to Malaysian currency. However, I suppose it also depends on the size, material and all that. It varies after all. I will not touch much on that as I have very limited knowledge on that topic.

Nevertheless, spoilers were invented to be assembled on high-performance sports cars. In layman terms, spoilers were not invented for your average Proton Saga, Proton Wira and so forth. Of course, if I am not mistaken the original design of a few saloon Proton cars have small spoilers as part of their designs to improve aerodynamics. The car was initially already designed to be stable. Modifying your average Proton saloon car by assembling a spoiler with a greater aspect ratio, you are basically increasing the downward force on the car. Hence, increasing friction and tract between the tires of the car and the surface of the road. In terms of "I assembled a rear spoiler to increase stability", highly unnecessary. There isn't enough lift force on a original, non-modified Proton saloon car that could cause it to be lifted up into the air and spun around. Think of the original downward force of the Proton saloon without any spoilers, it will take the application of hydraulics to spin the car around but still, it isn't going to stay airborne.

Seriously, an average Proton saloon travels at a speed of perhaps 60km/h and with the addition of a spoiler to increase the drag force, scientifically, more force will be needed to overcome the drag force. Some assemble spoilers on their Proton saloon car as part of 'decoration' but truth is, they are probably making the aerodynamics worse. This is because the spoiler is designed and engineered to "spoil" the airflow over a moving vehicle, meaning to decrease lift. Hence, skip the idea of putting spoilers on your Proton saloons unless you intend to start drifting. A spoiler for the price of a few hundreds and driving at the speed or 60km/h is just not worth the buy.

Now that (points at picture below) I like and probably (or certainly) would never own unless God makes me a billionaire. Where do I get one with a price tag that isn't 55,000 in US dollars that I can afford with my monthly allowance and that isn't a model set from the local toy store?