A week into getting our Prius, we decided that our trip home from Xmas in LA would be an opportune time to find out whether & by how much we could increase our mileage if we rode behind a truck, in its "wake". Insert disclaimer here about how this can be dangerous, do not try this at home, we were always following at a safe distance, etc. Here are the conditions and the approximate results (in a nutshell, yes it does increase, and by 10-15 mpg). THE DRIVE: Driving I-5 in California, btw Kettleman City and Hwy 152 (the exit for Gilroy), plus on 152 West for about 30 miles. On I-5, mostly flat and very straight. Outside temps were in the 40s with occasional showers. On Hwy 152, very hilly (one climb to 1400 ft), temps in high 40s with heavy rain. THE TRUCK: A 30' moving van, like a U-haul or Ryder truck but no Gramma's attic. I'd been looking for a good truck to follow since leaving LA, but the big trucks seemed to go too slow (do they know what you’re trying to do and slowed down on purpose?). As luck would have it, just north of the exit for Kettleman City, this moving truck passed me while I was going around 65 so I knew it was THE truck and pulled in behind it. There were two ways I compared my mileage. Method 1: eyeballing the “current mileage†number (in the “Energy†screen) for roughly 1 minute. To do this, one of us watched the “current mileage†(in the Energy screen) while the other drove behind the truck, and compared it to what we know it’s been before the truck came along. Because “current mileage†sometimes jumps around, we disregarded the brief fluctuations up & down, so not sure how accurate this is. RESULT: 35-45 mpg normally, 45-55 mpg behind truck, at speeds of 65-70 mph % INCREASE: About 20% Method 2: recording the “average mileage†number (in the “Consumption†screen) after following for a long time. I ended up following Mr. Truck for almost 2 hours. When we both exited onto Hwy 152 W, I followed him until we split at Hwy 156. So for approximately 120 miles, I was right behind him the whole time, passing when he’d pass and slowing when he’d slow, except a few times when it was safer to let a car between us; but I always got behind him again after a minute or 2. Our speed ranged from 60-80 mph (mostly 70-75 mph) on I-5, a distance of roughly 90 miles. On Hwy 152 (roughly 30 miles, very hilly, plus it was raining & very wet) we had big ranges in speed, from 35 to 70 mph. My average mileage over the 120 miles was 53 mpg. Based on mileage I’ve been tracking before Mr. Truck, or on my commute & elsewhere, I would guess that I get about 35 mpg if driving 65-70 for 90 miles; and around 44 mpg driving on a hilly road similar to Hwy 152. So… RESULT: 35-44 mpg normally, 53 mpg behind truck % INCREASE: 50% better at faster speeds, 18-25% at slower speeds So there you go folks. Please note that my calculations may be slightly off due to inaccurate memory (it was more than a week ago), but the numbers are as best as I could remember them. Also, I don’t mean for this post to become incentive for all Prius’ers to start tailgating a truck. But it does work, folks.
I can see the article in the July, 2005 issue of Trucker's Monthly: Why are we being tailed by Priuses? :lol:
LOL bookrats that's a good one! But hey the NASCAR guys do that every Sunday. When someone is tight on gas, just sit in second place till a lap or so before the finish and save gas then whip around the first place guy, slightshot is the correct term LOL, and win!
I do the 'drafting' thing whenever it is safe, ie. low traffic volume and clear highway. It makes a BIG difference. Maybe it has something to do with the shape of the Prius. I am curious if the truck has a corresponding drop in mileage.
Lets make a grapling hook for Prii. It could latch on to trailers of semi trucks. Make a emergency release that cuts the cable. Its a great idea. Latch on to get pulled, and whenever he's getting off a different exit, cut release the cable and get off your exit. Think of the possibilities. You could screw it into that hole in the bumper.
The car guys had a MIT physicist on some time ago describing the multiple drafting situation and all the trucks in a tight line get a benefit and the larger the group the better the milage they all get even the lead truck. Tom and Ray then offered if you had an infinite number of trucks you would use no fuel. The physicist was not will to go quite that far.
You Guys think you invented something new. I used to do this very thing with my 1963 VW 36hp Bug. It had no power on the highway especially up hills. I'd tuck in behind a big Semi-truck and us his draft, so I could actually go 65mph and barely touch the gas. It even helped up hill if I could stay in tight behind the truck. You just have to make sure they don't see you or have another truck rat you out. The truckers don't really like when your that tight on their rear ends.
That is why you use the alternate method. Not as effective, but still get a boost: stay on the side of the semi, up as far as you can with the driver's face clearly visible in his/her side mirror. Drop back when the truck needs to pass someone, creating a symbiotic relationship as you block all the cars that would try to pass if you were to pull ahead instead. Pull ahead if you are blocking traffic until it clears. You get the benefit of the truck "parting the air" and they don't get POed. I doubt this would work in LA, but on the open long haul cross country trips, it can be a 'good thing'. And, you don't have to worry about slamming into, then under, the trailer when he/she has to slam on the brakes for some reason.
In a parking lot, I saw a bumper sticker on the back of an Insight: [align=center:a4e5940731]I’m not tailgating I’m Drafting!![/align:a4e5940731] I draft when I can. But the view sucks and it does get boring fast. There are certainly zones to the wake. If you’re too close, it’s dangerous. Drift back and you are in the rough air where it is ‘regrouping’ and you get tossed around. But if you fall back a little beyond that area, you still get some advantage. I’m thinking it’s because the air is still disturbed and carrying some foreward movement. Side note, this does not work as well with Hummers since they have to pull over every few miles to refuel.
:lolup: :lolup: So, do long-distance Hummer trips require a gasoline truck to pull alongside and do a "mid-air refuel" every 200 miles or so?
