Drafting for MPG - Some Thoughts

One ancillary benefit of drafting or at least following a big rig is that they can act as a blocker for faster flowing traffic. If you want to drive at the speed limit or just below it then pop in behi d a big rig, leaving enough room between you both to be safe, and cruise at their speed. The traffic behind you would be forced to go around the big rig anyway so it's not like YOU are the one slowing traffic down. This is about the only way I can drive at 60mph without upsetting everyone on the freeway around me.

 

that's exactly what i like to do, great minds think alike!

 

65 x 1.4 x 2 = 182

 

F8L, exactly what I do, I follow the big rigs so traffic behind doesn't blame on me slowing down the flow.

 

10 car lengths?
Is that just a warning to persuade?

We used to draft way back when we were young and dumb, but
it was inches away from the truck...that pocket would literally pull you
up a steep incline, no problem.
Typically it was my friend that would do this, in a gas saving crunch for dumb reasons.

I was always told by my father to always keep one car distance (10 feet est) for
each 10 mph. i.e. 6 car lengths for 60 mph.

Anyway, driving the Prius 3 yesterday on the highway I came up on a
big rig and for giggles, I put it on cruise and closed in.
I am not sure if it was side wind or what, but the Prius just shuttered
and was a bit scary (with 2 kids in the back)
It didnt seem that I had lost control of any steering or braking,
but each time a car passed, it made feeling of the Prius..
a cheap light piece of crap. (for loss of words)
So I brought it in closer to the truck (up to about 2 car lengths)
and then eased back. Same deal.
I dont know if I couldnt find the pocket, or if it was due to side wind,
but I didnt try anymore.
Over all the total time was just a few minutes at most.

Of course I didnt do anything dangerous, but never experienced it act that
way. I will take it as side wind, not anything the truck or Prius was doing.

 

Use the 1 Min Consumption Chart, it gives you 5 times the feedback. I call it my 1 Minute Report Card. You get to it by just holding down the DISP button. It will toggle between the two every time you release and press again.

 

Your estimate is way off, because the Prius C is 13', so 10 lengths is 130'.

Personally (Prius 3) I keep about 1-1.25 seconds behind a larger vehicle. I find that the difference in the 1 Min Consumption Chart is about 15-20 MPGs better. At 60 mph for each second it's about 88'.

 

Please be aware that the Two Second Rule demands at least 176 feet at this speed.

In many areas this rule doesn't fit the reality of urban congestion, but other areas have plenty of room to obey it.

 

It's technically impossible to draft a big rig at high speed safely.

To be safe, you are too far back to get any drafting effect. To get any effect, way too close for safe braking. Add in chance of rocks or road debris coming at you too fast to avoid.

Better to buy a fuel efficient car and drive it safely.

 

On those RARE occasions that I draft big-rigs - they're usually going somewhat faster than I care to drive! - I tend to be at least 5 or 6 car lengths back, Mithril is set on "cruise control", I adjust speed with the "cruise control lever" ... AND ... my foot is ALWAYS positioned ever-so-lightly on the brake pedal, just in case! Even that "far" back - assuming the wind direction is conducive to such tactics - Mithril's mpg will tend to jump 5-to-15 mpg according to the instant read-out. Lastly ... I almost NEVER draft the same rig for more than 10 minutes or so, and I generally take at least a 20 minute break before drafting another one IF another one becomes available.

 

If the opportunity presents itself, PLEASE feel free to tell drivers of big rigs this. Collectively, "THEY" actually end up spending more time riding MY nice person - often at less than 20 feet! - than I do drafting them at 50-to-100 feet.

 

No it is a fact that you cannot meet safety parameters and draft a big rig at high speed.

It is your opinion that you wish to operate unsafely to save a few cents on gasoline.

Two different things.

 

I get a kick out of reading posts about safe following distances...I must be living in bazzaro world....2 second rule, car lengths per 10 mph. Try that by me on a major highway, commuting to/from work, and that 200 foot cushion is quickly reduced with 15 cars cutting you off. Right lane is no better with exits every mile and random people driving 10 mph under the posted limit and others 10 over (right up your rearend).

Forget about drafting, I'm just trying to keep out of other people's blind spots and making sure I have a move other than using my breaks.

 

At 55-65 mph you are 250-300 feet back and well out of draft.

 

You can try this website for suggested safe distances.

If you more the 100 feet back, there's not much drafting effect and at 55 mph, 240 feet is suggested safe distance.