Efficiency question

[DNAinaGoodWay]

Traveling ~65 miles, and all other things being equal, would it be more efficient to do 55 on the highway, with minimal stops and starts, or 30-40 on city and town surface roads, but with more stopping and starting.

Which would take more energy, the extra wind resistance, or the accelerating up to speed?

Actually, the surface road route is 8 miles shorter.

With the cold, 65 miles is all I'll risk, but luckily, that's where the QC is. All excited.

 

[philipscoggins]

Surface roads

 

[FerretPewPew]

Surface

 

[LeftieBiker]

Highway, if drafting a semi. ;-)

 

[philipscoggins]

He didn't offer the drafting option.
But yes, I find I can draft , at a safe distance, and get 5 miles/kWh (in the summer)

 

[DNAinaGoodWay]

Yeeeeaaaahh . . . . No.

Not with the famly in the car anyway.

I'm hardly ever up on the highway, so thought I'd ask.

But now I'm curious, what is a safe distance for drafting?

 

[planet4ever]

But now I'm curious, what is a safe distance for drafting?

You know the rule: 2 seconds minimum, 3 recommended. And if you are two seconds back you aren't drafting. In my opinion, there is no safe distance for drafting.

Ray

 

[philipscoggins]

I leave between 2 & 3 tractor trailer lengths between then & me. I talked to a friend who drives big rigs & he said that shouldn't upset most drivers. Also I only follow the ones that cruise at 65.
When I'm following, I don't read text messages on my phone or watch the scenery, I pay attention.

And it makes my interstate driving around 5.2 miles/kWh instead of mid 3s

 

[DNAinaGoodWay]

Interesting. So, there's a wake of turbulance that extends up to 3 trailer lengths behind? Enough to decrease your wind resistance and yield 5.2 in warm air? That sounds pretty far back. I've never studied it, but always thought drafting was done much closer, and more dangerously, like what Ray said.

 

[planet4ever]

I leave between 2 & 3 tractor trailer lengths between then & me. I talked to a friend who drives big rigs & he said that shouldn't upset most drivers. Also I only follow the ones that cruise at 65.

But according to Wikipedia, tractor trailer lengths (presumably in the US) are 28 to 53 feet. Since 65 mph is 95 fps, that means even 3 trailer lengths is only 0.9 to 1.7 seconds.

Ray

 

[apvbguy]

according to Wikipedia, tractor trailer lengths (presumably in the US) are 28 to 53 feet. Since 65 mph is 95 fps, that means even 3 trailer lengths is only 0.9 to 1.7 seconds.

Ray

the trailers can be up to 53' in length but the "tractor" can add almost another 20'

 

[DNAinaGoodWay]

So, 2 or 3 seconds is about the same as 2 or 3 lengths more or less, when I'm only eyeball estimating.

Never realized it, but by that standard, I draft a lot, for those few times that I'm on the highway. I stay in the right lane mostly and follow trucks, I'd guess within a length or two, never really knew that was drafting, just seems natural in our local highway traffic. (I thought drafting meant being about 3-6 feet back.)

Doesn't feel dangerous either. Mostly I'm in CC, keeping pace with the truck.

 

[philipscoggins]

I watched the myth busters guys cover it one time & while 3 feet might be optimal for pulling you along, all I'm using the truck for is knocking the wind out of the way & my m/kWh meter reinforces their findings.

 

[Tatertime]

i draft every day. Not too close, and never semi's. I have two uncles who drive truck and said they hate it. as you approach the other car you can hear a subtle change in the wind, and use two plus bubbles instead of four to keep up to speed. The best cars seem to be the ones that are newer, and the same overall size as the Leaf. Chevy equinox, newer Volvos, and caravans are the best. If its too big you can't see around it and thats not safe. The other day i traveled 23 miles and added 3 miles (71 to 74 when i got there) to my range, by regenerating on the downhills. I leave it in B mode because i can feel the regen better and quicker. I only regen one bubble as to not drift away from the other car too quickly. if you get up above 65 you get the benefits of extended range but can rarely regen as you drop back too quickly.

 

[TomT]

Not even close! At 60 MPH, each second is 88 feet!

So, 2 or 3 seconds is about the same as 2 or 3 lengths more or less, when I'm only eyeball estimating.

 

[Mottyski82]

Stick to the surface road and try to drive a steady speed. Avoid slow downs and stops, but if you can't avoid a stop, just start slowing down sooner so you don't actually come to a full stop, and so you have a rolling start instead.

 

[smkettner]

Stick to the surface road and try to drive a steady speed. Avoid slow downs and stops, but if you can't avoid a stop, just start slowing down sooner so you don't actually come to a full stop, and so you have a rolling start instead.

+1 and forget drafting.

 

[DNAinaGoodWay]

This thread is old. Just a commemoration of when our first NE QC was installed and I wanted to get there in the cold. It took a turn towards drafting, but now QCs aren't novel anymore and I don't bother with drafting. Now that it's not cold, I find I can set cruise control at 72 and stay in the middle lane on the pike and still do the 60 miles to Logan Airport with two bars to spare.