Dear Car Talk:
In the late ’50s and early ’60s, I think I recall seeing cars in southern California with straps hanging down under them, touching the road.
Were these straps really needed, and if so, what was their purpose? And, what changed, because you sure don’t see them anymore. — Paul
Fads come and go, Paul. Now, instead of hanging strips, we have decals of a kid peeing. The march of progress, right?
The answer is that they really served no purpose on passenger cars. They were decorative. Their purported purpose in the ’50s and ’60s was to discharge static electricity that built up in the car, so when you got out and touched the metal door handle or frame, you didn’t set off a 2-inch spark and straighten out your new perm.
But they didn’t do anything. Some people just thought they looked cool, and maybe believed the ad copy on the packaging.
Static electricity does build up in the car — especially when you drag your polyester pants across the seat to get out. But you already have equipment designed to take any static electricity to the ground: your tires.
There was a period, some 20 years or so ago, when manufacturers replaced carbon black, a very conductive material used to stiffen rubber tires, with a different stiffener called silica.
They switched to silica because it created less rolling resistance with the road. If you can make a tire that holds the road well when cornering and stopping but generates less friction when it’s just rolling along, you increase gas mileage.
But silica did a poorer job of discharging electricity, and some customers complained about static shocks. So, manufacturers have adjusted their formulas and now use enough carbon black to allow good static discharge.
But, believe it or not, these straps are still being sold. And somewhere, the bumper strap king’s great-grandchildren are sipping margaritas by a pool, enjoying their generational wealth. Along with their neighbor, the inventor of the mood ring.
Got a question about cars? Write to Car Talk write to Ray in care of King Features, 628 Virginia Drive, Orlando, FL 32803, or email by visiting the Car Talk website at www.cartalk.com.
