Welcome to Tesla Motors Club
Discuss Tesla's Model S, Model 3, Model X, Model Y, Cybertruck, Roadster and More.
Register

Massive efficiency gain when following someone

Jccope64

Member
Feb 24, 2020
36
20
North carolina
I have a long range model 3 with the 19 inch wheels, temperature plays a factor but I’ve noticed nothing plays as big of a factor as following kinda close behind someone to get great efficiency, I ran 82 mph for over 20 miles at 2-3 car lengths behind a SUV and averaged 240 wh/mi. Obviously that would increase efficiency just because your car doesn’t have to work as hard to push through the air but since you always see people complaining about how there high efficiency kills their range ,just follow someone running around the same speed as you . The 20 mile trip the opposite direction I ran closer to 65 without following and was closer to 285 wh/mi. There was not really any elevation gain/ loss or winds . Temp was 75f
 

swaltner

Active Member
Oct 13, 2012
1,630
1,678
Kansas, USA
Drafting vehicles is a well-known way to reduce aerodynamic drag in gas, electric, and human powered vehicles, as well as animals. It’s why bicyclists tend to ride in packs and why birds fly in a V formation. Mythbusters showed a 40% reduction is gas usage by tailgating a semi truck at something like 5 feet (on a closed course where the both drivers were in on the test).

It’s not without risks including higher risk of paint damage due to sand, rocks, and road debris getting kicked up by the lead vehicle, as well as front end damage to your vehicle when the lead vehicle either panic stops or brake checks you after getting pissed off for you tailgating.

If someone tailgates me at 2 car lengths on the open road, I usually just drop the cruise control by several mph or how ever much I need to get them to pass.
 

Jccope64

Member
Feb 24, 2020
36
20
North carolina
Drafting vehicles is a well-known way to reduce aerodynamic drag in gas, electric, and human powered vehicles, as well as animals. It’s why bicyclists tend to ride in packs and why birds fly in a V formation. Mythbusters showed a 40% reduction is gas usage by tailgating a semi truck at something like 5 feet (on a closed course where the both drivers were in on the test).

It’s not without risks including higher risk of paint damage due to sand, rocks, and road debris getting kicked up by the lead vehicle, as well as front end damage to your vehicle when the lead vehicle either panic stops or brake checks you after getting pissed off for you tailgating.

If someone tailgates me at 2 car lengths on the open road, I usually just drop the cruise control by several mph or how ever much I need to get them to pass.
Per Tesla cruise control, their idea of 2-3 car lengths is pretty far back , definitely not tailgating
 

Big Earl

bnkwupt
Supporting Member
Jul 12, 2017
5,956
11,287
Springfield, VA
Per Tesla cruise control, their idea of 2-3 car lengths is pretty far back , definitely not tailgating

So you’re following at 2-3 Autopilot distance units, not car lengths. 2-3 actual car lengths would be downright dangerous.

Yes, drafting can save a lot of energy. The trade-off, as mentioned above, is paint and windshield damage from sand and other road debris.
 

mswlogo

Well-Known Member
Aug 27, 2018
6,183
5,339
MA, NH
If someone tailgates me at 2 car lengths on the open road, I usually just drop the cruise control by several mph or how ever much I need to get them to pass.

That’s exactly what I do too. What drives me crazy is when I slow 5mph and they stay put. Slow another 5mph and still there. Now I’m going 50mph in 65 mph speed limit. Finally I pull into the left lane so they pass. Then I’m stuck behind them because now they are driving slower than I was. Pass them again and you see them with a flip phone plastered to their ear.

Can’t tell you how many times something along those lines has happened. I’m not a speed demon. But I like space in front and behind.
 

Atari2600

Active Member
Oct 4, 2017
1,051
959
Cincinnati
I think three actual car lengths behind a semi should be safe on autopilot. The only way a semi could stop faster than a Tesla would be if it hit a wall. It’s still rude though. Follow actual 6 car lengths and I think it’s fine.
 

markap77

Member
Feb 20, 2020
24
23
Central Indiana
Per Tesla cruise control, their idea of 2-3 car lengths is pretty far back , definitely not tailgating
The Tesla cruise control follow distance isn't based on distance, it is based on time.

From the Model 3 owner's manual about the follow distance settings:

Each setting corresponds to a time- based distance that represents how long it takes for Model 3, from its current location, to reach the location of the rear bumper of the vehicle ahead of you.​

Therefore, the distance that the cruise control will use will vary depending on your speed; closer distance at 50 mph than at 82 mph.
 

smartypnz

Supporting Member
Supporting Member
Jan 23, 2013
2,198
2,388
Monterey Peninsula
Cyclist 'Mile a minute' Murphy was known for being the first cyclist to go 60 mph on a flat surface. Trouble is...
Murphy.png


He cheated
 

smartypnz

Supporting Member
Supporting Member
Jan 23, 2013
2,198
2,388
Monterey Peninsula
We are a software delivery away from being able to join a "train" where a group of cars coordinate to run in a high speed lane as a single unit. Lead car would be compensated for breaking wind and all in group would benefit from gang drafting.
Software would maintain bumper to bumper spacing and manage "join and exit" maneuvering.

That should keep the blood flowing.
 

MrMassTransit

Supporting Member
Supporting Member
Mar 7, 2019
299
515
Washington, DC
My experience is that efficiency gains are very possible while following at a completely safe distance - a distance that exceeds what most drivers allow - with vehicles of sufficient height. At highway speeds, I would never follow a vehicle at less than 4 seconds time, with 5 seconds being ideal (how many car lengths that is depends on the speed of traffic). Yet on these threads, I see many raise safety concerns about this behavior. I tend to drive pretty close to the speed limit - also to improve safety and maximize efficiency. I'd rather find a vehicle that's traveling about my speed and stick behind it, rather than being isolated in the right lane with drivers passing me on the left and then cutting back in front of me.

As long as everyone is maintaining a safe following distance for the speed they are traveling, I fail to see the issue. Rock and debris damage is a legitimate concern, though.
 
  • Funny
Reactions: GoSharks

jpfive

Supporting Member
Supporting Member
Oct 31, 2019
558
538
Pensacola, FL
I think three actual car lengths behind a semi should be safe on autopilot. The only way a semi could stop faster than a Tesla would be if it hit a wall. It’s still rude though. Follow actual 6 car lengths and I think it’s fine.

Here's another consideration. I've been told that truckers, especially, do not appreciate this, as they know you are there and have to be diverting their attention to that fact. My uncle was a long haul trucker, and I know he felt that way. Also, there is another hazard that you perhaps have not thought about. If you are close behind a semi you can not see items in the roadway that he might strike and throw up into you. In the case of cars, perhaps a different situation, but I would prefer you not do it with me. It keeps me focusing too much on my rear view mirror. My $.02
 

DrSmile

Member
Nov 7, 2018
234
150
Northern NJ
As an avid cyclist I can tell you that the aerodynamic gain from drafting extends further back from a vehicle than you might expect, but the gain increases significantly if you're within the wake zone of negative pressure. On a bike I can be quite far behind say a landscape trailer and be in that wake zone, in a car you can be back quite a few car lengths of a truck trailer and get a significant benefit. A caveat people might not consider is that often there might be a significant cross wind that will move the draft zone laterally, so you may actually get a better draft being in the adjacent lane. Obviously that comes with other concerns like holding up traffic and being in the truck's blind spot.

Having said all that I don't draft in my model 3 for the reasons mentioned, but on my bike I draft pretty much anything I safely can, especially in head wind conditions.
 

dmurphy

Supporting Member
Supporting Member
Dec 7, 2018
3,831
5,416
New Jersey - Morris County
Here's another consideration. I've been told that truckers, especially, do not appreciate this, as they know you are there and have to be diverting their attention to that fact. My uncle was a long haul trucker, and I know he felt that way. Also, there is another hazard that you perhaps have not thought about. If you are close behind a semi you can not see items in the roadway that he might strike and throw up into you. In the case of cars, perhaps a different situation, but I would prefer you not do it with me. It keeps me focusing too much on my rear view mirror. My $.02

If you can’t see the tractor’s mirrors, they can’t see you back there, either.


Back off till at least both mirrors are in sight.
 

Products we're discussing on TMC...

About Us

Formed in 2006, Tesla Motors Club (TMC) was the first independent online Tesla community. Today it remains the largest and most dynamic community of Tesla enthusiasts. Learn more.

Do you value your experience at TMC? Consider becoming a Supporting Member of Tesla Motors Club. As a thank you for your contribution, you'll get nearly no ads in the Community and Groups sections. Additional perks are available depending on the level of contribution. Please visit the Account Upgrades page for more details.


SUPPORT TMC
Top