Originally Posted By: eljefino
I remember when car ads listed drag coefficients. I would like to see that return. I specifically remember a ford LTD II from that vintage claiming it could push through the air at 50 mph with only 7 hp. Wow!
That's actually about average. For a long time, Car and Driver magazine listed road horsepower requirements at 30, 50 and 70mph for all cars tested. At 50mpg most cars of the era ('80's, maybe early '90's until they stopped doing it) required about 15hp to go down the road, about half of which was air drag and half rolling drag. At higher speeds air drag becomes the dominant factor, but not at fifty.
It is interesting that Ford was being a bit loose with the facts, implying that 7hp was all that was required at that speed, whereas a specific reading of the wording indicates the certain truth that the 7hp is what is required only to overcome air resistance. The total, as with other cars, was probably 14 or 15 or so.
Two decades ago, a .30 Cd was excellent, but many cars are in the high twenties these days. Definite progress. Of course, many more people now drive trucks, which are obviously way worse, so maybe no progress, really.
By the way road horsepower required at seventy is on the order of 35. Throw in a hill, though, and you might need 100hp or 150hp to maintain that speed. It is the need to climb hills at speed that really affects the amount of hp needed. Of course a lot of cars have way more than is needed these days no matter what conditions you consider.
