enzojr

I've always been curious as to how close you have to be to the car in front of you in order to draft them in real-world settings (let's say at 100km/h/ 60 mph on the hwy). From listening to the amount of wind noise, there doesn't seem to be much difference, if at all, by following closely to the car in front of you.

Also, is it better to slipstream an aerodynamic car or a big rig? The big "How to maximize your fuel economy" thread suggested big rigs but I avoid following them in fear of huge rock chips or windshield chips.

Any thoughts?

joerockt

I'm no aerodynamisist (sp?), but I'm pretty sure that once the air passes the end of a car, it starts to baffle. So unless you're literally inches away to allow the air to flow over your car as well, you're always going to be in disturbed air.

LuvMyTSX

You should probably repost this in Car Talk. Not really TSX-specific.

CarbonGray Earl

Unless your stopped, anything remotely close to drafting is going to be tailgating in the real world. If I were the driver in front of you - I'd probably spray my windshield washer on you, and brake check you.

And yes.....this is not TSX specific.

taylor314gh

watch mythbusters, they just did this experiment. I think mpg was up about 45% 15-20 feet behind a semi. If gas mileage is worth dying for, then go right ahead and drive that close.

hornedfrog2000

I would guess within 3 feet. This wouldn't be smart though, because it will probably cause an accident.

evolpe

I read an article on MSN about feul economy. There's a group of people that strive to ge the most fuel economy out of their vehicles, modding them to sometimes get more than 505 increase on the vehicle's posted mpg. I can't find any of the articles online right now but one of the things they mentioned was drafting other vehicles. They were saying drafting vehicles very closely (like you see in Nascar) isn't beneficial or safe at all. They suggest following a tractor trailer by a few car lengths if you choose to draft. They say getting closer will increase your gas mileage, but is it worth the added risk? Also, if done improperly (constantly braking and accelerating to adjust to the changing speeds of the vehicle in front of you) you can cancel out all potential benefits of drafting. They said to get the most out of highway driving to drive the posted speed limit behind another driver doing so and let fast cars pass to the left. This does three things. 1) You're driving at a speed that closely maximizes fuel economy (I get better fuel economy doing 55 mph than doing 75 mph) 2) the car in front of you is reducing some of the air friction in front of you and 3) as cars pass you they pull you along with them.

I know this works because before I read this article I drove to the shore and got 28 mpg averaging over 70 mph. Then I followed the directions in the article and recorded 33 mpg traveling at an average speed around 60 mph.

jswim99

I'm no aerospace engineer, but I took plenty of fluid mechanics courses through school; I think the turbulent air is actually what you want to be in. Basically there's less drag through turbulent air. This is why golf balls have dimples, they induce turbulent flow and the ball goes farther.

rb1

I drive a lot with my sunroof and/or windows open, and I notice a significant difference in buffeting and wind noise from the windows and roof even quite a few car lengths back from a car in front of me. Even 2 seconds of distance behind an SUV or van, it makes a big difference.

Deity711

I'll spend the extra bucks and get lousy fuel mileage if it means I have to ride behind a semi and possibly get my windshield cracked or something.

r33p04s

the only thing worth drafting behind is a semi...not suggesting you do it at all but it is an experience to behold...you can actually let off the gas and feel the semi pull you along slightly before the weight of the car is too much for the vacuum to hold...but the rock chips etc. are def. not worth it

Zoopa

You should be close enough so you don't see the guys tires in front of you anymore, then look away from the road and check your MID for the gas mileage to improve. If it doesn't improve then you still gotta get closer...just pretend that your watching NASCAR on Speed Channel and your racing on an oval.

enzojr

My bad - still getting used to this board! I'll leave it to the mods if they would like to move this thread, thx!

evolpe

The truth about drafting is significant gains are only achieved when traveling at extremely high rates of speed. It takes much more energy to propel a car to 200 mph and maintain that speed. That is why it is so adventageous in Nascar because the lead car has to use all that energy whare as the one trailing behind by a few milimeters uses significantly less. When traveling at 60 mph the difference in energy spent maintaining that speed isn't enough to warrant drafting.

rb1

^^^^



In my last car, a 15 mph headwind would cost me 3+ mpg, or roughly 10%.

I think there is some savings to having a car at a modest distance ahead of you (e.g. 10-12 car lengths) at highway speeds versus just blazing your own path down the road.

Just because the draft isn't strong enough to tow your car all by itself (e.g. practically attaching yourself to the rear of a semi) doesn't mean that you can't get some benefit.

JTso

iTrader: (2)

Wrong forum, please post in "Car Talk".

https://acurazine.com/forums/car-talk-5/