Q: Dear Greg, my question is regarding aerodynamics and high speed on ordinary passenger cars.

I see so many older coupes and sedans with high output engines and my gut feeling is that the car will never stay on the road at speeds over 100 mph.

Out here we have 80 mph speed limits on I-84 and my 2008 Honda Accord feels light at that speed. If there is any head wind or cross wind, I back off.

It would appear without air dams, spoilers or lowering kits that the station wagon body is probably better suited for higher speeds than a coupe or a fastback. It would seem that by design, you would have the same air effect at the top and bottom of the vehicle thereby neutralizing the air lift effect.

Could you comment on this and also the many street rod builders that go overboard on engine installs?
ó Wayne Adams, Payette, Indiana.

A: Wayne thanks for your hand-written letter dated November of 2016 and Iíll sure try and do my best to answer it.

First, I have to compliment you on your ideas about aerodynamics and how you apply them when it comes to understanding what many auto manufacturers found out by trial and error early on. Second, all of this answer is my non-professional personal opinion.

Specifically, the cars that were built through pre World War II had little or no aerodynamic touches unless you were talking Duisenberg or the many cars that were built to run the Bonneville Salt Flats back then. And most important, even though those early speedsters were considered very aerodynamic, it would be many decades later when things like wind tunnel testing were used regularly for car construction and auto racing body modifications.

But hereís what is both surprising and inspiring. One of the early day auto designers was Harley Earl who came from a World War II aircraft experience background. It was Earl that got things moving for General Motors with his aerodynamic designs that would become common in the late 1940s through the mid-1950s. Iíll also note Nash, Kaiser and Studebaker, all of which released more aerodynamic inspired models. You mention that many of the older coupes and sedans didnít seem capable of staying on the road at 100 mph, but I remember a friend of mine drove his 1954 Oldsmobile to a NASCAR recorded time of over 130 mph on the Daytona Beach speed trial course with no handling problems. These Oldsmobiles were a far cry from todayís outstanding Mustang, Camaro and Corvette designs, but it proved a point that a decent design, weight in the right places and so on would keep your car on the road.

However, this 130 mph Olds doesnít mean these cars were great handlers by any means. The early day fast cars were built to go straight, and it you tried planting one of them in a turn at 75 mph you could find yourself in a heap of trouble. The problem back then was lack of tire technology, suspension sophistication and no aerodynamic testing. Terms like drag coefficient and downforce were clearly only used when building airplanes, although the German brands, Mercedes-Benz and Porsche especially, led the way with aerodynamic testing as far back as the 1950 decade.

As we fast forward to the modern day cars and wind tunnel testing, most all cars are built to go straight and handle well at higher speeds. Crosswinds and head winds can play havoc on many modern day cars (race cars, too) so all things considered the cars of today are safe and sound at higher speed in the right hands. Thatís why we feel like weíre going 50 mph but the speedometer says 75. This all comes about thanks to computer simulated aerodynamic and/or wind tunnel testing.

Additionally, when you look at the underside of a 2017 Mustang or Corvette you find that these cars have aerodynamic design attributes underneath the car as much as they do above the car. That 80 mph speed limit on I-84 is nothing for these cars, which can travel at 140 mph plus on the Autobahn and still feel glued to the road. This comes thanks to wide, traction hungry tires, unique spoiler treatments, performance suspensions, grilles that have fins that close at speed and rear wings that move automatically for better down force as speed increases.

And speaking of downforce, itís one of the two major areas of aerodynamics while the other is drag coefficient. A designerís objective is to reduce drag and any undesirable ďliftĒ properties that would affect keeping the car on the ground. Thatís why the top performance cars today are totally aerodynamic both underneath as they are on the exterior body design. When you add roof racks, mud flaps, side mirrors, and even windshield wipers or a radio antenna, your vehicleís drag and downforce is impacted negatively.

In ending, Iím not sure about those station wagon styles of yesteryear, but todayís wagons are indeed all very aerodynamic and safe. I test drove a Cadillac CTS-V station wagon (no longer available) about 4 years ago and I had it over 135 mph on a closed circuit speedway with no problems. The CTS-V wagon did not have a big rear spoiler, just a very small extension. (You may be correct in your wagon airflow theory).
As for the street rodders who go overboard with engine installations, thereís nothing better than a 1966 Chevelle SS with modern day underpinnings like an 450-horse LS crate engine and tranny that delivers 25-mpg. If itís a T-Bucket hot rod you speak of, Iím not a fan.

Hope this helps, Wayne, and thanks for your letter.
ó Greg Zyla writes weekly for More Content Now and other Gatehouse Media publications, He welcomes reader questions or comments on collector cars, auto nostalgia or old-time racing at 303 Roosevelt St., Sayre, Pa. 18840 or email at greg@gregzyla.com.