Do spoilers serve a purpose, or are they just for show?

Dear Car Talk | Feb 01, 1995
Dear Tom and Ray:
Barry
RAY: The main purpose of spoilers is getting dates, Barry. Of course, it's never worked for me, even though I've had a spoiler on the back of my '87 Dodge Dakota pickup truck for years.
TOM: Theoretically, spoilers do serve a marginally useful purpose. They're designed to use the wind--when the car is travelling at high speed--to force the rear end of the car downward. That's supposed to help keep the rear wheels planted more firmly on the pavement, which helps you maintain traction.
RAY: And the reason that's useful, even with front wheel drive, is that no matter which wheels are powered by the engine, it's still a good idea to have all four wheels on the ground...Jim Rockford notwithstanding. Even if you're driving a front wheel drive car, you want those rear wheels firmly on the ground for cornering, braking, and just plain stability.
TOM: But the truth is, at 55 or 65 miles an hour, spoilers don't do much. They're designed for race cars that take corners at 120 miles an hour... speeds at which wheels can actually start to lift off the ground. And in those situations, they can really make a difference. But in day to day driving, they serve the same societal purpose as tattoos and hair-replacements.
Barry
RAY: The main purpose of spoilers is getting dates, Barry. Of course, it's never worked for me, even though I've had a spoiler on the back of my '87 Dodge Dakota pickup truck for years.
TOM: Theoretically, spoilers do serve a marginally useful purpose. They're designed to use the wind--when the car is travelling at high speed--to force the rear end of the car downward. That's supposed to help keep the rear wheels planted more firmly on the pavement, which helps you maintain traction.
RAY: And the reason that's useful, even with front wheel drive, is that no matter which wheels are powered by the engine, it's still a good idea to have all four wheels on the ground...Jim Rockford notwithstanding. Even if you're driving a front wheel drive car, you want those rear wheels firmly on the ground for cornering, braking, and just plain stability.
TOM: But the truth is, at 55 or 65 miles an hour, spoilers don't do much. They're designed for race cars that take corners at 120 miles an hour... speeds at which wheels can actually start to lift off the ground. And in those situations, they can really make a difference. But in day to day driving, they serve the same societal purpose as tattoos and hair-replacements.
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