it doesn't relieve pressue, it increases the pressure by "spoiling" the air flow over the vehicle, as you yourself pointed out. Since you have a problem with my visual, I'll post one from your source. The image below shows that when the spoiler is deployed, the side which it is deployed is pushed down. It is the exact same principle on race cars with the spoiler set to as much as 60-70 degrees, it creates downforce by disrupting the air flow over the rear of the car.

 

i hate to do this to you but those are not the spoilers those are the aelerons. they also have the wing like features to them.

 

irrelevant, the end result is the same. they deflect the air flow over/under them, resulting in movement in the opposite direction of the side which the pressure is increased. It's the exact same thing a spoiler does on a car. Even looking at the second image you posted in your initial post, it clearly shows my point. Lift up the right spoiler, increases the pressure over the right wing and pushes it down.

So like I said, your contention is half right, it does decrease lift by way of creating downforce, which is the downward pressure created by the aerodynamics of the car as it travels forward.

 

yes it does have a downward movement because of less lift, that is right, but it is not due to increased downforce which is created by the wing, to your logic a spoiler, as you would like to call it is acctually a static aeleron(or angled wing if you will) with alters the direction of the air behind it which brings in the angle of attack concept

which in the end is in fact a wing with an angle, so the "spoiler" on the top left of the monte is acctually like an aeleron and the whole care has the lift effect. damn that just ****ed everything up. well everyone keep calling it what you want to call it, but heres a lil explination of the different parts involved in aerodynamics
Bernoulli's Princaple

theory behind lift and downforce.

ailerons <-- correct spelling,


spoiler


overview of parts of an airplane



btw when you said about the ailerons. the ailerons use angle of attack(altering the angle of the wing in order to modify the amount of pressure of each side) the spoilers just ruin the lift.

 

I have an idea for you, stop referencing planes, we're talking about cars.

Yes, lift is decreased by use of a spoiler. This is due to less of a difference in air pressure at the top of the car vs. the bottom. The resulting downward pressure is called downforce. There is no other way to decrease the lift of any given vehicle by way of something mounted on top of the vehicle, if it's mounted on top and decreasing lift, it's creating downforce.

 

RiFrechSS, Blue SSteel looks incredible! I would love to have my grill & front dam look like that.. Where did you order that, or how did you customize it?