is it better to go with the flow on the hwy?

[diamondlarry]

Before I came to this site, I would cruise at 80+. But I've since slowed down -- in addition, I've taken a more laid-back driving attitude around town. I never let the car next to me accelerate faster at a light, but now, what's the hurry? It's a paradigm shift that I really needed.
RH77

Hey Matt, do you still have the link to that book(Take Your Foot Off the Gas?) that was on here awhile back? Maybe it's time to bring that back?

[MetroMPG]

If you've ever had to pull-over to the side of the Interstate (to change a tire, etc) -- you can feel that wall of air hit your vehicle as the high-speed vehicle passes by.

that was actually my original point, which i don't think i made very clear by the amount of objection to it...

my suggestion was simply that with enough traffic volume, the "wall of air" does indeed move. enough vehicles will actually generate a current of air which moves along the road. they effectively create a localised "tail wind" which benefits everyone in the flow.

if enough vehicles are contributing, you don't even have to get particularly close (drafting) to benefit from it. let's say theoretically this current of air is flowing at 30 km/h. at 100km/h your apparent head wind is now reduced to 70 km/h.

you won't benefit from it if you're driving alone on the 80 km/h side road. you're actually using more fuel there because your apparent head wind is 10 km/h stronger than in traffic on the freeway.

[rh77]

I think I see where you're going -- sorry I didn't elaborate on it I was too busy ranting about the physics of high speed driving. For fuel consumption, airline pilots calculate flight plans and ranges using head/tail winds and fuel consumption at particular throttle positions. So a busy highway would have a significant "tail wind" with the perpetual motion of constant traffic, and could theoretically push you along given the right conditions. Also like fluid dyanamics -- stirring a cup of coffee, and the stir-stick follows the "current" around the cup for a while after you stop stirring.

This is complicated stuff -- but intruiging. Measuring the wind speed in the lane of movement would require a non-intrusive device like Nexrad radar (it measures the inbound and outbound speed of air). My gut feeling is that vehicles create vortices after they pass, and disrupt the airflow. More research is needed...

RH77

[SVOboy]

I should also mention that insight owners not only draft, but ride the wake of other cars. This would mean getting up on the side of a truck and finding where the wake of the air pushingness will help reduce drag, and it works! (according to the guy who tested with scangauge.)

[rh77]

I consulted a physics friend of mine, and found some interesting thoughts on the subject. Consider the following:

* Geese fly in a "V" pattern because the wind resistance is less for the birds further back

* If you show an extreme slow-motion of a rock falling into water, a cavity it created before the water fills the water displaced. If you keep dropping rocks in the same spot back-to-back, the void remains, and it would take less energy to move the following rocks through the same "hole" (read: flow of constant traffic).

You may be onto something here. Is the fuel savings significant enough to conduct an official "experiment" here folks?

RH77

[Matt Timion]

Originally Posted by rh77

You may be onto something here. Is the fuel savings significant enough to conduct an official "experiment" here folks?

RH77

My only concern on this one is safety. Insight drivers get right behind Semi trucks and draft off of them. That scares me. I'm not certain I'd be willing to do something like that. I also like having space to the left and right of me in the event I have to change lanes suddenly. Driving in a V-pattern might prevent it.

Something like this would be very difficult to control as well. Person A might be "bird drafting" (my word for driving in the v-shape) off of a Hummer, and person B might be bird drafting off of a semi. Person C might be doing it off of a Excursion. Results are going to vary quickly.

I would be interested in anyone's results using a scangauge however, as it allows you do bird draft for a minute or two and see if your instant mpgs increase or not.