Which is more important? Drafting to save a little energy, or having to fix a front end that got peppered by pebbles, or perhaps an exploded tire tread? Or even worse, you submarined under when the truck hit something making it stop far faster than you thought possible? Everyone can make up their own minds, obviously, but I consider it unsafe and the benefits far outweigh the negative consequences, so I try to stay far away from semis.
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Proper "Drafting" Technique?
- Thread starter Boomer543
- Start date
Absolutely yes.
It's risky to MAXIMIZE the drafting savings, because the savings go up as you get closer, right up until you're less than a foot from the target vehicle. VERY risky.
However, if you follow a larger vehicle at a safe distance, you also save - in comparison to following a smaller vehicle, never mind in comparison to being a lone car.
So yes, if you can choose to be behind a van instead of behind a compact car, you will save. If you choose to be behind a compact rather than in a solo lane, you will save.
Little bits do add up, as long as you can be smooth with the accelerator.
Atari2600
Active Member
Is following on autopilot set to distance=1 dangerous? The answer is no as it increases the distance as you go faster to avoid collisions.
Drafting at safe distances behind semis can yield over 20% savings. i have observed this very carefully the last 10 years first with a Ford Fusion hybrid and then with a Tesla both of which have high precision energy usage displays or trip counters. Tesla's can do this very safely on AP/EAP with following distance set at any level. Following SUVs and minivans is almost as good and your vision is not blocked as much. Crosswinds tend to reduce the effect. In this kind of drafting the front vehicle does not get much or maybe no help like in NASCAR.
Any moderate to heavy traffic provides a boost as the vehicles create a tail wind. Airspeed is very critical to M3s. You can use the same wh/m at 80 in a convoy in the left lane as by yourself at 70 in the right lane.
Any moderate to heavy traffic provides a boost as the vehicles create a tail wind. Airspeed is very critical to M3s. You can use the same wh/m at 80 in a convoy in the left lane as by yourself at 70 in the right lane.
AlanSubie4Life
Efficiency Obsessed Member
You have to be careful about extending the results of that test to an EV, because on an EV a much larger percentage of the loss is due to aero. The more efficient the vehicle, the greater the % improvement. At 80mph nearly 2/3 of the resisting drag (Wh/mi has units of force) is aero loss in Model 3!
Anyway, I would guess that even using maximum following distance on AP behind an SUV, which if not drafting in the traditional sense, you will see some improvement on efficiency.
It’s pretty routine to see better efficiency in Model 3 in moderate traffic, all else being equal.
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exactly I got ppf as well. No way am I gonna follow trucks, big suv, lifted trucks. I avoid it. I drive on the fast lane just to avoid big rigs.
AlanSubie4Life
Efficiency Obsessed Member
I avoid following at any distance behind vehicles without mud flaps. Which is apparently all pickups and most SUVs.
I almost feel like there should be a law.
On the other hand, the last time I got hit by a rock, it was from a Porsche GT3 with sticky tires in the next lane over, a significant distance ahead.
So now I also don’t follow anyone who is likely to be using autocross/max performance summer tires.
Overall it is a real pain. Makes me realize how many pickups, SUVs, and lifted vehicles there are out there.
Anyway, drafting works. You don’t have to follow dangerously closely to get some benefit. 3-second rule works fine.
KrenGrl
Banned
One thing for sure is your can expect more rock chips over time. To me it isn't worth rafting and risking an accident of being too close.
I wonder what are people drafting try to accomplish ? Saving a 10 minutes stop at a supercharger ? Saving a few bucks on a trip ? Are you guys so tight on time and money ? Really ?
I hate when somebody is close behind me. I actually tap the brakes to light up the rear lights when it happens. It is just dangerous. Even with the AP. We all know that it is not 100% reliable.
I hate when somebody is close behind me. I actually tap the brakes to light up the rear lights when it happens. It is just dangerous. Even with the AP. We all know that it is not 100% reliable.
What's the three second rule? That's over 100 yards at 70 mph. The car can come to a dead stop in about 1/2 that distance. The TACC will give you emergency braking even.
AlanSubie4Life
Efficiency Obsessed Member
Note that braking distance goes up with the square of velocity!
California Driver Handbook - Visual Search
“To avoid tailgating, use the “3 second rule”: when the vehicle ahead of you passes a certain point, such as a sign, count “one-thousand-one, one-thousand- two, one-thousand-three.” This takes approximately 3 seconds. If you pass the same point before you finish counting, you are following too closely.”
Fortunately you can do this and still benefit significantly from drafting.
A lot of excellent info there, for example:
You should allow for more space when:
- A tailgater is behind you. Allow extra space ahead and do not brake suddenly. Slow down gradually or merge into another lane to prevent a collision with the tailgater!
I wish Autopilot would do this second part! It already does the first (following time is adjustable, not really distance, I think).
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Wouldn't that be called...drafting? If your efficiency is increasing because you are following another vehicle, at whatever distance, because of being in the displaced air from the leading car...then you are technically drafting.
