I tried drafting with my Sentra when i first got interested in hypermiling, on a 1000 mile drive to New Mexico. Basically, I got about 37 mpg, the same as I get going 60 mph without drafting, but I go a little faster following the trucks. Now I tend to just go 55 mph, and get about 40 mpg.

Drafting definitely works. I used to ride a 90 cc motorcycle with a top speed of 70 mph downhill with a tailwind. When i was struggling up hills, or fighting winds, my top speed dropped to 55 mph. When semis would pass me, I'd tuck in behind them and they'd suck me up to 70 mph. The best suction was about a car length off their bumpers, in the lane next to them. Once I dropped farther back, the suction was gone, and it was like riding in still air, until I dropped about 10 car lengths back and the turbulence started.

xBs are like pushing barn doors into a 60 mph wind. Letting a truck do the work for us has to help our gas mileage.

 

LOL. I believe that's also their "blind spot." If you're that hot to have an accident with a big rig, why don't you save yourself the suspense and just drive into the truck yourself?

Seriously, though: as I said a year ago, Mythbusters definitively proved that 50-100 feet is great for improving your mileage, with the added benefit of not pasting a target to the side of your vehicle. I'm sure you could also get better mileage by removing the windshield and all the windows of your vehicle, but that's in approximately the same category of Bad Ideas.

In conclusion: no reason to do something as ludicrously unsafe as lurking in a semi's blind spot, but yes, drafting works. BE SAFE, people!

 

Not to mention if they were to throw up a road gator or some other debris.

 

Slipstreaming in the next lane isn't unsafe. If the semi changes lanes, he's still a car length or two ahead of you, so what's dangerous about that?

When I'm poking along at 55 mph, sometimes 2-3 seconds behind a semi, I get passed all the time by impatient hotheads. 70% of them don't have a 2 second gap between them and the car they're tailgating. Many times, you could squeeze three of them in the space between me and the semi in front of me. THAT's unsafe! It's also insane.

 

Just though I'd share this:
Draft works on a concept call boundary layer separation. Because of the sharp edge on a semi trailer, streamline flow separates from the trailer creating a low pressure region know as the wake region.

Since pressure drag is indirectly related to the difference in pressure between two points (ie the front and rear of the vehicle), having a low pressure up front would decrease the difference in pressure. I am not sure how to calculate how long this wake region is, but i assume the closer you are whiling drafting, the more effective.

 

Also, the the drag on the car is 1/2 x density of air x relative velocity of the car squared x frontal area x coefficient of drag. The drag coefficient of the xb is about .35, which is average. But the down fall is that is multiplied by the frontal are which is larger than an average car.

So i great way to reduce drag is to take of the windshield and hatch and drive with airplane goggles on, reducing the effective frontal are of the car.

That would probably be safer than drafting a semi. lol

 

I'd rather have the first chopped top xB. Until then, I'll just drive slower.

 

In case I didn't make it clear, I don't draft. I get better mileage going slow. I confirmed that drafting works 37 years ago. Last year, I confirmed that drafting 2 seconds back is 3 mpg worse than simply going 5 mph slower.

 

I have had several semis draft behind me...

 

how do semis get any type of draft speed or advantage from drafting behind a scion? mdove is full of it. and I dont draft cause its dangerous, to get real results u have to be pretty close, if you are trying to save gas. Keep ur scion in one peice kids.

 

blademonkey....you really do need to get a sense of humor!!!!

 

any time you change the areodynamics you can call it drafting.

semis drafting behind a scion xb saves them a bit of fuel by adding an air dam. The scion being smaller will act like an addition to the front making them more aerodynamic .

especially after smacking into it and making it a permanant addition.
Xb as a hood ornament. as long as it ain't mine.

 

frog box....you got it....

 

I do the same on my trips from NC to NY. but i'm usually a good 100 ft behind the tractor trailer. i don't have cruise and i think that's what keeps my mileage on the up and up. unfortunately the speed limit in NC is 70 and in top gear cruising at 70 the motor is screaming so i only average 31-33 mpg per tank.

 

On a recent trip to St. Louis from KC (~270 miles) our group stayed fairly close together. Nothing too extreme, but still close. Simple math (miles on tripmeter divided by gallons put in) said I was getting ~ 32-34 MPG at 70 MPH. Not too shabby considering I normally get about 26 MPG.

 

I actually got better mileage traveling 75 behind a semi than going 65 without. The scangauge doesn't lie.

If you're 100 ft. behind a semi you are NOT in his blind spot. Even if he hits the brakes you can outbrake him.

Drafting can be done safely and with a significant savings in fuel.

 

Nothing, I suppose, as long as the driver doesn't take his foot even a milimeter off the gas pedal, because if he does, the time it would take one of you to strike the other is less time than a human takes to blink.

I realize the Rules of the Road say you should accelerate while making lane changes, but depending on a spaced-out trucker to follow traffic rules to the letter, while running a heartbeat (or less) away from an accident, is not my cup of tea........... especially when I could be getting the same mileage advantage 90 feet back.

At least if you're behind him you've got a chance...if you're hanging out in the blind spot you could have impact before you even realize you're having an accident.

 

Haha... I've been fantasizing about this for the last few months! My first job was working at a body shop with some guys who would build hotrods from the 30s (3 window Ford Deuces) and the first thing they would do is chop it... I think it would look so cool and mpg would be through the roof!

On another note - I've been reading up on hypermiling and the best I've done on a single tank is 36... I think I need to get better at driving, but 46? That's crazy!

 

I drafted some kind of box truck once on the way to work on the freeway. I didn't have anything to measure MPG, but the whole ride felt different because the wind resistance just wasn't there.

 

I've been away for a month touring Peru. No worries about drafting there! First, most of the country roads are dirt, and you only see a handful of other vehicles/day on them. Second, city traffic is the worst mix of congestion and unobeyed rules you'll ever experience in your life.

20MPGXB, there's a reason you only get 20 mpg ;). If you're in the next lane two car lengths back, and the trucker changes lanes, you're supposed to slow down ;) and increase your safety margin. No need to start 90' back.

pluckmyeyesout, my wife and I are short people, and we could easily live with 6" less headroom on our xB. Chopping the top might hurt resale value, but I'll bet the coolness factor will actually increase the value more than lowering the car, and putting 19" wheels on it. I'm going to measure my headroom, and see just how much can be removed. If there's really a lot of wasted room, the chopped xB would really look a lot better, IMHO.

Yes, I'm really getting 46 mpg over the last 645 miles, since I bought the xB. 167% of the EPA estimated combined mpg isn't unusual. I'm getting the same % increase (actually 169%) over EPA with my Sentra - over 9000 miles of driving. And I'm doing it without drafting.