Drafting safely could save a lot of fuel
Avid hyper-milers and NASCAR drivers already know that following closely in the slipstream of another vehicle can reduce the amount of energy it takes to maintain a given speed. Drafting is a known phenomenon but researchers in India wanted quantify how much of an impact it really has. At Jadavpur University they put four cars into a wind tunnel and found that the second car in the series would need twelve percent less fuel to maintain 50 mph and the third and fourth cars needed twenty-one percent less fuel.
They don't say how close the cars were too each other but it was likely a lot tighter than would be prudent on public roads with unknown drivers. The only way this might be practical in the real world is when cars are equipped with vehicle to vehicle and vehicle to infrastructure communications to preemptively warn of potential problems. Even then there are far too many variables such as road conditions, different drivers and other obstacles to make such close following a viable practice.
[Source: AutoExpress]
Reader Comments (Page 1 of 1)
Scatter 8:50AM (7/23/2007)
Not just vehicle to vehicle communications but completely automated driving. Taking the human out of the loop will make this possible and at higher speeds. I can see it coming in in the future at least for motorway driving. I quite like the idea of being able to put my feet up, read a book and have a drink while the computer does all the tedious work!
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Kardax 8:55AM (7/23/2007)
Most of us can't afford to wreck our cars every few weeks like NASCAR drivers do.
I agree with Scatter--fully-automated driving is necessary before drafting can be a common practice in the public.
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amg 12:28PM (7/23/2007)
For those who know the series, there was a Mythbusters episode where they tested drafting behind a big rig and found that improvements in MPG were noted even at a distance where people normally follow them (which is still closer than recommended). The improvement increased as the distance between the car and truck decreased. I wonder how many of us have unintentionally improved our fuel economy by following the car/truck ahead of us closer than we should.
I also think that computer controlled highway driving is the way of the future, but I imagine it will take quite a bit of time to get used to the idea of letting my car drive for me when I'm actually in the situation!
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scappy 1:13PM (7/23/2007)
My since departed neon used to get around 34 on the highway. One week I decided to drive quite conservatively and draft some big rigs on the highway. I managed to achieve 41 mpg.
I'm not condoning drafting rigs, but their stopping distance is much greater than a car so in theory it is possible to drive closer to them.
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ooglek 2:28PM (7/23/2007)
Mythbusters did this test:
http://www.tennesseegasprices.com/Forum_MSG.aspx?master=1&category=1054&topic=266901&page_no=6
In real tests, MPG went from 32 to 36 at 100ft, and 32 to 39 at 50ft behind a semi.
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Dave Gregory 6:06PM (7/23/2007)
When I was driving to work, I would short shift, clutchless shift, draft behind semis, and run in neutral behind the semis down the 5 mile hill to work. It worked really well especially when I didn't have any money for gas.. I could stretch a fill for almost 2 weeks.
Although it worked quite well, I also can't condone doing those things. I found it necessary at times, but didn't make a habit of it, because of the lack of safety. Also I am quite sure truck drivers get a little ancy when a miata is only 30-40 feet behind them.
Thankfully, I use public transportation for my new job and I feel much safer that way.
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another Bill 2:33PM (7/24/2007)
If your car has an instant fuel economy readout, it's very easy to do this, and you don't have to follow dangerously close to get benefit.
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