People have covered coasting and optimum speeds... now we can talk about another extreme way of saving gas: drafting!

Race car drivers, cyclists, and even runners stay behind each other to reduce aerodynamic drag, and the beneficial effects it has on gas mileage has been confirmed by many people, including the show 'myth busters'

You can draft other cars, SUVs, but the you get the most bang for the buck by drafting behind a truck with a huge profile. To achieve maximum effectiveness you gotta get pretty darn close, but you can achieve pretty significant mileage improvements even when you're 2 car lengths away.

Back when I drove a maxima, according to the MID, I was able to squeeze an extra 3MPG (more than 10% improvement) by following a truck. I made sure I drove the same speed and I only had the balls to follow at about 1.5 car lengths.

Of course this could be dangerous, but I figure I can stop a hellava lot faster than a truck and whatever hazard is in front of us will be plowed over by the truck first =P Other cons to this include rock chips and a pissed off truck driver when he realizes you've been in his blind spot for 50 miles.

 

drafting in real world = epic fail. that is the stupidest most dangerous thing i've ever heard of.

when you are traveling behind a big rig you cannot see in front of you. there is no way to know what's up ahead. you are assuming your reaction time can make up the 1.5 car length distance. also, have you seen race cars and motorcycles draft/slipstream? they are kissing bumpers. you need to be *close* otherwise, the air molecules that are passing over the car in front of you will just reform and hit you anyway because the profile of the tail wind is turbulent. there's a reason why cars have rear spoilers/wings/deflectors - its to control the tail end of the air passing over/under race cars. unless yer' kissing bumpers, there is no real benefit to you since you are not in the pocket.

worst of all, your front end will look like swiss cheese with rock chips. not a good idea on a car with soft paint.

 

hah,

I agree with all you said minus the part about the effectiveness of drafting when more than a few inches away. Since I think the most scientific real-world study done on this matter is by mythbusters (which isn't all that scientific), it's the only source I can cite besides my own experience: http://mythbusters-wiki.discovery.co...rafting?t=anon

They only ran one trial per distance, so there's nothing to say of chance and error, but there's a pretty clear trend of efficiency increase up to even a whopping following distance of 100 ft.

Air behaves just like water, except it is much less viscid, so just imagine an object plowing through a pool... it will leave a vacuum in its wake. Additionally, wind resistance increases cubically with driving speed, so the wind resistance at 60mph is 64 times that of 15mph... deflecting even a small portion of that wind will save you gas.

On most days I see most people following pretty closely to other cars anyway... might as well get behind a big truck and save some gas. Like I said before, if the truck needs to stop, there's no way in hell it'll stop faster than you can. Moreover, you can achieve pretty significant mileage increases with 3, maybe even 4 car lengths which is decently safe at 60mph. As for the rock chips, maybe you'll be driving a beater one day and you'll think of tihs post...

 

i have no patience for following a slow car, let alone a trucker..

 

Recommending people to tailgate; I always hit the brakes when I'm being followed closely. Let's see how your fuel economy improves with all the hard braking and quick accelerations.

If you can't see the mirrors of a big rig, the driver can't see you. And if it kicks up any rocks, you'll be sure to get it at full speed. Cops do pull people over for tailgating.

 

I'm just going to say that if you're alert and have quick enough reflexes, the TSX will stop a lot faster and easier than a big rig.

Personally, I don't like rock chips.
And I once was behind an 18 wheeler where the spare jarred loose and came rolling my way. Scariest moment of my life.

 

Just because the TSX can stop faster than a truck doesn't mean you can see what's ahead of the truck. If the truck makes a quick lane change to avoid an accident in front of him, you won't have time to react if you are following too close. This method of gas saving is simply not practical.

 

Out of the few posts I have, most are dedicated to gas mileage. I have discussed drafting on several occasions. While traveling for work, I notice that most big rigs go a few miles over the speed limit- which is perfect for me when Im getting paid mileage. Ill set my cruise at a few car lengths behind and have never seen to aggravate them. I can achieve 30+ mpg easy. I often feel like Im getting pulled, but that requires a closer distance than Id like.
While not working, Ill be in the left lane and usually be in a caravan of SUVS (it seems everyone in the south has suvs/ trucks). Ill be second in line and we are typically all close together. This seems to help mileage also, but not as much as the cruise control method- tight formations of cars make it difficult to regulate speed.
HOWEVER, i purchased my car CPO with no chips. Within 3 months of interstate driving i had several. I patched them as best I could with the paint pen and got the clear bra. Also got LAMIN X film for the fogs. Now it seems like all probs are solved.

 

well, according to mythbusters, even at 55mph the wake at 100ft will help you increase gas mileage by 10%... if you find a truck going 70mph i'm sure the wake will be even bigger. and 100ft is a little more than 6 car lengths.

 

 

Very dangerous advice! Talk to any EMT or cop. Major trouble ahead for you if you do this often. Think about it, travelling 60 mph is 88 ft/ second. Your 3-4 car lengths is travelled in half a second. I hope you never take your eyes of the back of the truck, not even for a second. Not worth the savings in my book. Want to save money? Drive less.

 

Accidents, Injury, Death ,,,,,,, arent we missing the most important down fall ROCKCHIPS!!!! lol

 

werd. following a truck is one way to royally screw up your car's paint job.

 

Okay, so you save a few cents per tank of gas. Is it worth it to put yourself in a risky situation? How about for your passengers? I don't care if Mythbusters or Dr. Bunsen Honeydew proved that this works, it's just asking for trouble. Take a driver's ed course or talk to a few seasoned highway cops about this before your encourage others to do it.

 

i find it hard to believe you always keep more than 100 ft from the car in front of you.

and no, i don't encourage people to do it for the sake of saving a few cents... there's something awesome and addictive about squeezing mpg's out of the car.

 

I admire your passion. Therefore, I challenge you to find other ways to improve the mileage such as keeping the car properly maintained, remove unnecessary items from the trunk, install lighter wheels, tires, or even install underdrive pulleys to make your engine work more efficient without putting the public at risk.

 

rock chips from behind a truck ftl

 

Stupidest idea EVER.......death, severe injury, rock chips, etc. are not worth saving .5 gallons of gas.

 

maybe i should look into this

http://www.water-4-fuel.com/

 

At the risk of being flamed, I made a habit of doing this for 4 days straight. Here's the deal....

I commute 100 miles per day and I do it in a 97 Prelude that can best be described as battle worn. Chips on the hood are no longer a concern on this car. I get about 29.4 MPG doing this commute.

I decided to see if I could push it up into the 30's by getting behind a truck on the highway and sticking relatively close. If you turn the radio down, you can hear the rushing air decrease as you slip into the sweet spot. As the experiment progressed I was figuring about 33-35 MPG results were coming.

At 100 miles per day, I blow through a tank in 4 days and after 4 days of drafting, I was getting a whopping 29.5 MPG. Big freaking whoop, wasn't worth it at all.

 

perhaps you were traveling at different speeds?

 

If anything, I was slower when drafting. I'm typically rolling at about 75, but it's tough to find a semi going over 70 around here. I certainly wasn't able to go faster when trailing an 18 wheeler.

I am a firm believer in the benefits of drafting after experiencing them 1st hand in shifter carts, but in road cars at highway speeds, I can't find a benefit.

 

Or Safe. I always instinctively jab at the brakes if i notice somebody "Drafting"

 

imagine if airplanes used the drafting technique ... YIKES

 

geese do it...


on a side note, i can't believe the government hasn't stepped in and put an end to these 'water as gas' scams

 

Based on sunroof wind noise, I think there are drafting benefits just to having a larger vehicle a safe distance in front of you (safe = the standard 2 seconds).

When I have the roof open, it's much noisier without a car or truck in front of me than if I'm following someone, even if I'm not tailgating.

 

You're kidding, right?

 

You draft behind a truck going 70mph, in the winter it sounds like it is RAINING because of all the sand and rocks being flown up onto your car.

Yea no thanks.

 

correct

 

^^ just checking

 

I can tell you guys from riding motorcycles, the wake of air left behind big SUVs and trucks extends way, way back. Several hundred feet on calm days. It's very easy to tell when you're in the dirty air when it's smacking into your entire body at 70 mph.

From just my empirical observations, the semis tend to stir up the wind to such a degree that you have to be very, very close to get any real benefit. It feels like the air coming around the trailer just collapses behind it and tumbles about in large vortexes. You get buffeted around a lot unless you are way dangerously close.

The big SUVs seem to poke the largest, stable holes in the air. It's like they drag a big tail of air behind them so that when it hits you, it's already moving in the same direction thus decreasing your relative wind speed. You sit pretty high on a bike and sometimes I can see straight through the windshield of the vehicle in front of me so it's a lot more comfortable being close. My idea of close is at least 2 seconds back though.

In a car though, your frontal area is so much bigger that you have to be a whole lot closer to stay inside that wedge of moving air. There's no way it's worth the risk to save a buck or two every tank.

 

all the science of drafting/slipstreaming aside - have you seen a big rig lock their brakes and fishtail because of an emergency or ever see them blow their tires out? trust me when i say you do NOT want to be near them. same can be said for any big truck. the risks are too great to save a few pennies.

i think the majority here value their safety AND their paint!

 

I generally like to keep a 4-second or better following distance. If my math's right, at 70 MPH that's about 410' back. 2 second following distance (the minimum I'll close to), 205'.

Been there, done that. Got caught in a Falcon 20's vortices while doing intercept training. We lost about 750' of altitude in 2 seconds. I watched a life raft levitate, hover in front of my face as if to smash me, then fall back down with a huge thud. Very scary. Took a minute or two for my soul to catch up with me. (Read PATTERN RECOGNITION to get that reference.)

 

didn't your msf instructor tell you to stay 4 seconds behind and scan 12 seconds ahead?

 

Indeed. In fact I usually leave a much larger cushion when I'm riding than I'm in my car (which is still huge by most people's standards). There's zero margin for error on a bike whether that be your own error any one else's. It doesn't matter whose fault it is, the guy on the bike loses.

 

mind as well just sell ur car and take the bus

 

You can follow a large truck at safe distances and still accomplish frafting, but more to the point, most people here never keep a safe following distance anyway. When I'm on the freeway maybe 10% of the cars apear to deliberately follow the three second rule, so the people who are writing it off as entirely unsafe are mostly driving unsafe to begin with and only hate the idea because it's on purpose in this case.

According to Myth Busters the savings were very significant, the guy driving the '97 Prelude was doing something wrong. I usualy don't draft because big rigs go significantly slower that the rest of traffic and if a cop somehow figures that you're doing it intentionaly he can give you a ticket.

 

Just remember, if you are too close to anyone in fromt of you, whatever they throw up will cream you. Example, I was following a car in I-30 at plenty of distance when he ran over one of those rubber cargo deck mats some big rigs have on their load beds. It was runover safely by him, but it lifted as it passed under the car...I ducked right but still took a hit to the nose of my Z3 that put a mightly crease in it, knocked out the grills, and scratched the crap outta the bumper. I was sufficiently far behind, but the car to my left forced me to go right...unfortunately the mat drifted right too!

In my TSX (2 days old), I was sufficiently far behind a car when he pounded over a big chuck of concrete. The chunck came out from under his car splting into three pieces...I broke right, away from traffic and toward the middle sized piece (the biggest went left, second biggest right, smallest straight on) figuring if I went straight all three might get me. The piece dinged the crap outta my underengine tray and the lower bumper...but if I'd been closer it would have probably been a piece in the grill as they bounced out from under the car running them over.

 

Are you, sir, making disparaging comments about your peers on this board? Are you making the assumption that because we discourage following trucks too close (not 2 seconds or better, but right behind), we MUST be tailgaters.

What is it with you kids, if we don't agree with you, you suddenly brand us as tailgaters and reckless drivers, without ever having met us?

 

Dont want to argue too much here, but I got the best mileage by setting cruise several car lengths behind a big rig for a couple hundred mile trip. I know everyone here says follow longer distances, but in Louisiana it is not an option. We only have 2 lane interstates and everyone seems to follow closely. Its not good, but with congested highways there aren't many options.
The scary part is the damn road debris you cant see. One time I was in the interstate and a tire fell off a truck 100 ft in front of me and start bouncing up and down the interstate- could've easily smashed my windshield but thankfully I avoided it. I had enough distance to see it fall off the truck. Anytime trucks have loose stuff in beds i NEVER follow closely.