Viewing a single comment thread. View all comments

Numerous_Oils t1_irl56nd wrote

Reply to comment by Camero466 in TIL about The “Victory Speed”. Beginning in May of 1942 and ending in August of 1945, a nationwide speed limit of 35 miles per hour was instated. The “Victory Speed” limit was instated in order to reduce gasoline and rubber consumption. by Phillip_Lipton

Air resistance ruins gas efficiency past 55 mph, it worsens quickly any higher.

Highway speed is better MPG due to (as I recall) other cars already cutting that air for you, essentially paving a less resistant path through the air, making that travel at higher speeds more efficient. So it's not so much the speed, but cars in front of you cutting currents through it to make it easier.

In general, the lower the speed, the less air resistance, the greater the efficiency.

At really low speeds, like 5 mph or whatever, you're burning more gas than you're using to move the car, energy wasted. 35 mph is the first generalized "sweet spot" and the next is 55 mph.

1

Flaxmoore t1_irne0f6 wrote

And a lot of cars in that era had terrible drag coefficients- even the fairly sleek Beetle.

1

Numerous_Oils t1_irnhlmh wrote

The fact that modern cars aren't more thoroughly streamlined is still silly to me.

Give me a giant pill, man. Screw the aesthetics.

1

Flaxmoore t1_irnrf9d wrote

And it takes very little to change the efficiency.

I had a car bra for my 3 series- E36, the last of the boxier models- and with nothing more than smoothing out the bumper/fender transition and adding a couple small wedges to direct air a little I got a full mile per gallon highway improvement.

That's over a full summer of testing, with the same drives done over 50 times. Held up nicely- 30mpg highway without it, 31 with.

1