What Wh/mi are you getting with AWD and P cars?

[dfwatt]

Look at this thread. Look at the numbers. Literally every person reporting over 300Wh/mi average is on 20s. You're denying what's starting you in the face.

The 20s are not "low rolling resistance tires". They're sport tires. They're stickier than the 19s, which are stickier than the 18s. Suspension losses are a real, meaningful thing. Spinning wheels store a meaningful amount of energy. Non-aero wheels are an aerodynamic disaster zone. But forget about all this. Even forget about what Tesla has directly told you. Just look at the numbers staring you in the face in this thread.

Denial is not just a river in Egypt.

And meanwhile people on the 18s with aero caps average in the mid 200s and sometimes even less on the highway. depending on what speed you call "highway speeds".

The importance of wheel selection is demonstrably real.

You're making counterfactual claims about the 4S. Go talk to someone at Tire Rack. More importantly and beyond the factual issues, I'm not in denial and this style of debating is offensive.

 

[spinbackwards]

Here's my data.

Oh. P3D 20" wheels.

 

[djgarrett21]

@KarenRei I disagree. You're attributing a ~17% increase in efficiency to the aero caps (Crr plays a much lesser role at freeway speeds). At freeway speeds yaw angle (incident angle at which the air hits the car) is probably going to be within the +/-5 deg range - essentially head on. The frontal area and profile of the car is going to have a much more significant impact on aero drag than in a location such as the wheels which are parallel to the flow. In my experience a feature like the wheels would have a very minimal impact, like 5% or less.

A CFD could get you in the ballpark but only a full on wind tunnel test would give you real data. If I have some extra time and can find a decent representation of the M3 I might create a simulation and do a few runs.

If we're comparing RWD to AWD then then I'd say there is much more evidence pointing to the extra motor in the front consuming power and decreasing efficiency than the shape of the wheels and their contribution to drag.

 

[medx]

I haven't driven much, 60 miles over the past week, but I'm getting terrible range so far. Mostly city miles. I've been driving it soft, like a Prius instead of a Porsche, trying to get the range figured out. I charged 30 miles the other day and it's already gone with driving 11 miles & phantom drain.

AWD with 19's.
AC on auto @ 74
Tires 40 psi front, 41 psi back
avg. 371 Wh/mi

 

[KarenRei]

You're making counterfactual claims about the 4S. Go talk to someone at Tire Rack. More importantly and beyond the factual issues, I'm not in denial and this style of debating is offensive.

Pilot Sport 4S tires are EU efficiency class "E" (scale A to G, A is low energy consumption), but wet grip class A. That's a sports tire, not an eco tire.

 

[KarenRei]

I haven't driven much, 60 miles over the past week, but I'm getting terrible range so far. Mostly city miles. I've been driving it soft, like a Prius instead of a Porsche, trying to get the range figured out. I charged 30 miles the other day and it's already gone with driving 11 miles & phantom drain.

AWD with 19's.
AC on auto @ 74
Tires 40 psi front, 41 psi back
avg. 371 Wh/mi

That brings up another issue: people, when reporting your energy consumption, please don't mix phantom drain in with it.... make that a separate category...

When people keep jumbling in more and more variables, they just make their individual results more and more comparatively meaningless.

 

[medx]

That brings up another issue: people, when reporting your energy consumption, please don't mix phantom drain in with it.... make that a separate category...

When people keep jumbling in more and more variables, they just make their individual results more and more comparatively meaningless.

I'm assuming it's phantom drain...371 Wh/mi speaks for itself though.

 

[kbecks13]

My RWD Model 3 could routinely hit 220-240 wh/mi when cruising on highway at ~70mph.

New P3D+ with 20" rims is getting ~300 wh/mi when cruising around 70mph, though I think i can probably get this down to 270-280 if i wasn't so aggressive and/or take longer drives with a greater percentage of steady-state cruising.

Also - This thread feels like it's trending towards bickering/arguments, could we please not go down that route? @KarenRei @dfwatt plz

 

[KarenRei]

@KarenRei I disagree. You're attributing a ~17% increase in efficiency to the aero caps

No. There's about a 10% difference going from the 18"s to the 19"s. Slightly under half of that is directly attributable to caps on vs. caps off on the 18s

The frontal area and profile of the car is going to have a much more significant impact on aero drag than in a location such as the wheels which are parallel to the flow

No. Wheels are a nightmare when it comes to automotive aerodynamics. See the generation of turbulent flow here for an example:

They're terrible, but cars have to have them. So you go through great lengths to try to minimize their impact.

(The front of the car is actually the simplest and most straightforward part of the design, and among the least sensitive parts of the car to deviation from the optimal airfoil-shaped cross section)

 

[djgarrett21]

No. There's about a 10% difference going from the 18"s to the 19"s. Slightly under half of that is directly attributable to caps on vs. caps off on the 18s

No. Wheels are a nightmare when it comes to automotive aerodynamics. See the generation of turbulent flow here for an example:

So you agree with me, about 5% (as long as we're throwing out completely unsubstantiated numbers). When it comes to a vehicle, I'd consider that to be very far from a "nightmare".

Regarding the linked videos, flow fields are nice for visualization (and dazzling those impressed by pretty pictures) but can be deceiving and aren't going to give you a measure of performance.

 

[dfwatt]

I haven't driven much, 60 miles over the past week, but I'm getting terrible range so far. Mostly city miles. I've been driving it soft, like a Prius instead of a Porsche, trying to get the range figured out. I charged 30 miles the other day and it's already gone with driving 11 miles & phantom drain.

AWD with 19's.
AC on auto @ 74
Tires 40 psi front, 41 psi back
avg. 371 Wh/mi

How many miles though do you have on the entire powertrain. For the first 50 miles my mileage was pretty bad and now around town I'm getting 220-240 miles per Watt hour – but forget about it if I goose it. Enjoying the phenomenal performance kills your mileage. Although even at 371 you're still getting the equivalent of 100MPGE. If after 100 miles and driving around town you can't get 250, then it might be some kind of issue. On the highway though your mileage is always going to be less, and the faster you go the worse it gets.

 

[TEG]

@KarenRei I disagree. You're attributing a ~17% increase in efficiency to the aero caps (Crr plays a much lesser role at freeway speeds). At freeway speeds yaw angle (incident angle at which the air hits the car) is probably going to be within the +/-5 deg range - essentially head on. The frontal area and profile of the car is going to have a much more significant impact on aero drag than in a location such as the wheels which are parallel to the flow. In my experience a feature like the wheels would have a very minimal impact, like 5% or less.

I think you may be considering how much air from the front of the car is hitting the wheels (maybe not so much), but I think of the "eggbeater effect" where the wheel blades are just churning at the air. I think the aero covers may make them spin more easily. As a test, someone could put the rear wheels up on jacks, and rev the motor to get the wheels to spin at 75MPH equivalent and measure the difference in energy used to spin them with and without the covers on.
(In this case, car won't give you any meaningful wh/mi since you aren't moving...)

 

[KarenRei]

So you agree with me, about 5% (as long as we're throwing out completely unsubstantiated numbers)

A) With respect to only the 18s with caps vs. the 18s without caps. Not with respect to the 18s with caps vs. the 19s or 20s.
B) Only with respect to that one aspect, not with respect to differences in tires or unsprung mass. As mentioned, the net difference between the 18s with caps and 19s without them is about 10%. The 20s are even worse.
C) They're not "unsubstantiated numbers", quite a few people have run this test and arrived at similar numbers. You can find both threads about it (this forum, Model 3 forum, probably Reddit too) and videos on Youtube.

Regarding the linked videos, flow fields are nice for visualization (and dazzling those impressed by pretty pictures) but can be deceiving and aren't going to give you a measure of performance.

They're not supposed to. They just show where you're screwing up your airflow. You don't want that sort of vorticity anywhere near the front.

BTW, just to correct something written earlier: while in a simplistic presentation rolling drag force is presented as constant with respect to speed, it isn't. It's relatively constant at low speeds, but starts curving up significantly at highway speeds, particularly high highway speeds.

 

[medx]

How many miles though do you have on the entire powertrain. For the first 50 miles my mileage was pretty bad and now around town I'm getting 220-240 miles per Watt hour – but forget about it if I goose it. Enjoying the phenomenal performance kills your mileage. Although even at 371 you're still getting the equivalent of 100MPGE. If after 100 miles and driving around town you can't get 250, then it might be some kind of issue. On the highway though your mileage is always going to be less, and the faster you go the worse it gets.

70 miles on the odometer. Probably 85% city, 15% highway so far. Back and forth from the gym last night, 2 mile round trip - 588 wh/mi...not even driving hard.

I went straight to a Super Charger station when I took delivery, since the car only had half it's charge. I was only getting 34 kw or 133 mi/hr charge, which I thought was crazy low, so I swapped chargers and still had the same speed. I asked two Model S' what they were getting for speed and both were over 250 mi/hr in the same chargers I was using.

Have a service appointment on Monday, so going to ask them to check the battery while it's there.

 

[dfwatt]

70 miles on the odometer. Probably 85% city, 15% highway so far. Back and forth from the gym last night, 2 mile round trip - 588 wh/mi...not even driving hard.

I went straight to a Super Charger station when I took delivery, since the car only had half it's charge. I was only getting 34 kw or 133 mi/hr charge, which I thought was crazy low, so I swapped chargers and still had the same speed. I asked two Model S' what they were getting for speed and both were over 250 mi/hr in the same chargers I was using.

Have a service appointment on Monday, so going to ask them to check the battery while it's there.

What is your ambient temperature? Unless this is way out there and you're using either a lot of air conditioning or a lot of heat, 588 is a crazy number for anything other than driving most of your trip slightly uphill (the mileage differences between slightly uphill and slightly downhill are stunning!), or going batsh-- fast on the highway. It does sound like a good idea to have it checked out. I haven't used the supercharger yet (we got a home charging station installed which works like a dream), so I'm not in a position to comment on what that might mean, but it does sound crazy low. Something appears amiss.

 

[medx]

What is your ambient temperature? Unless this is way out there and you're using either a lot of air conditioning or a lot of heat, 588 is a crazy number for anything other than driving most of your trip slightly uphill (the mileage differences between slightly uphill and slightly downhill are stunning!), or going batsh-- fast on the highway. It does sound like a good idea to have it checked out. I haven't used the supercharger yet (we got a home charging station installed which works like a dream), so I'm not in a position to comment on what that might mean, but it does sound crazy low. Something appears amiss.

74 degrees on auto, fan is usually on speed 2, sometimes on 3. Going there (gym) has a small uphill stretch, so coming back should maybe offset.

 

[dfwatt]

74 degrees on auto, fan is usually on speed 2, sometimes on 3. Going there (gym) has a small uphill stretch, so coming back should maybe offset.

yes, it should, and there should be a big difference between those. but your average between the two shouldn't be more than 275 whr/mi. On my downhill run to the tennis courts a mile or so away, I can get 100 whr/mi. Or even less. Way back, 400+ whr/mi.

Where do you have your regen braking set?

 

[medx]

yes, it should, and there should be a big difference between those. but your average between the two shouldn't be more than 275 whr/mi. On my downhill run to the tennis courts a mile or so away, I can get 100 whr/mi. Or even less. Way back, 400+ whr/mi.

Where do you have your regen braking set?

Regen is set to Standard. Any type of aggressive driving sets me into the 600-1k+ Wh/mi range.

 

[dfwatt]

Regen is set to Standard. Any type of aggressive driving sets me into the 600-1k+ Wh/mi range.

Something for sure seems amiss. Good that you have a checkup coming. I'd just review all this with the service techs and see what their computer hookup reveals.

 

[AnarchyEOD]

I’m not sure if the last update did it, or I’ve really figured out how to optimize revenue, or I drive like a grandpa... but I’ve been getting 210-220 the last few days and I’ve put about 200 miles on the car. I’m not mad about it at all... oh, 3D on 18’s w/no caps.