Real World Comparison of a S85 to an 85D Efficiency

[breser]

Repeated the trip from yesterday today using range mode. It was colder and was raining lightly when we left but the rain didn't last long and most of the trip was still on dry roads. As you'll note we did a little worse on this trip with a little shorter distance this time. I took a route that matches what EVTripPlanner does so I didn't have to put an extra way point in there to trick it to go the way I wanted. So despite going a little less distance we used a tad more energy. I'm guessing most of that is the heating. Same 70°F cabin temperature the whole way and 400 lbs of carbo.

Location	Time	Temperature (°F)	Rated Range (miles)	Battery %	Trip Estimated Battery %	Energy Used (kWh)	Efficiency (Wh/mile)	Distance
Home (Leaving)	15:07	59	237	88	64	0	0	0
Wallace Falls State Park (Arrival)	16:25	58	187	69		14.1	269	52.3
Wallace Falls State Park (Departure)	18:07	56	186	69	44	14.1	269	52.3
Home (Arrival)	19:35	51	129	48		29.9	288	103.7

Average speed from Home to Wallace Falls was 40 mph, Speed multiplier of 0.975 on EVTripPlanner equals this. Average temperature on this trip was 59°F. Trip to Wallace Falls is a drop in elevation of 351 feet (per EVTripPlanner).

Average speed from Wallace Falls to Home was 35 mph, Speed multiplier of 0.85 on EVTripPlanner equals this. Average temperature on this trip was 54°F. Trip from Wallace Falls is a gain in elevation of 289 feet (per EVTripPlanner).

Comparison against EVTripPlanner:

Results from	Distance	Driving Time	Energy Used (kWh)	Energy Used (RM)	Efficiency (Wh/mile)
Actual to Wallace Falls	52.3	1:18	14.1	50	269
EVTripPlanner (85D 19" tires)	50.6	1:16	11.2	37	221
EVTripPlanner (85 S/P 19" tires)	50.6	1:16	11.8	39	233
Actual from Wallace Falls	51.4	1:28	15.8	57	307
EVTripPlanner (85D 19" tires)	50.5	1:28	12.3	41	244
EVTripPlanner (85 S/P 19" tires)	50.5	1:28	13.0	43	256

Comparison of deltas between trips and EVTripPlanner

Delta between	Distance	Driving Time	Energy Used (kWh)	Energy Used (RM)	Efficiency (Wh/mile)
Actual to Wallace Falls (No Range Mode) EVTripPlanner (85D 19" tires)	101%	115%	125%	133%	123%
Actual to Wallace Falls (No Range Mode) EvTripPlanner (85 S/P 19" tires)	101%	115%	117%	126%	116%
Actual to Wallance Falls (Range Mode) EVTripPlanner (85D 19" tires)	103%	102%	126%	135%	122%
Actual to Wallace Falls (Range Mode) EVTripPlanner (85 S/P 19" tires)	103%	102%	119%	135%	115%
Actual from Wallace Falls (No Range Mode) EVTripPlanner (85D 19" tires)	104%	103%	137%	149%	131%
Actual from Wallace Falls (No Range Mode) EvTripPlanner (85 S/P 19" tires)	104%	103%	130%	141%	124%
Actual from Wallance Falls (Range Mode) EVTripPlanner (85D 19" tires)	102%	100%	128%	139%	126%
Actual from Wallace Falls (Range Mode) EVTripPlanner (85 S/P 19" tires)	102%	100%	122%	133%	120%

From what I understand EVTripPlanner was usually within 10% for people with S85s. If that's the case then then 85D is still using more energy even in range mode than an S85 based on this testing.

One note on the rated miles. They are taken with range mode off to be consistent regardless of how the driving was done.

 

[Andyw2100]

From what I understand EVTripPlanner was usually within 10% for people with S85s. If that's the case then then 85D is still using more energy even in range mode than an S85 based on this testing.

I'm more interested in why your efficiency didn't improve with range mode on. Do you think the temperature difference was enough to completely overshadow any efficiency gains from torque sleep?

Actually I just did some quick calculations from some of your numbers. You can do more if you like if you think I am mistaken, but it appears you actually -DID-- see an efficiency improvement from range mode.

I only looked at the wh/mi numbers for your four legs--to and from each day-- and compared them to the EV Trip Planner numbers you provided for the 85D. And doing that, you were closer to EV Trip Planner's predictions today.

Actual wh/mi	EV TP Estimate	% above EV TP Estimate
Friday
253	205	18.97
294	225	23.47
Saturday
269	221	17.84
307	244	20.52

I think using the % difference from EV Trip Planner as the equalizing metric we can all use to compare things works.

Some of the P85D owners who are seeing major improvements after torque sleep are beating EV Trip Planner estimates by 8-12%. Well, I should say they were beating the Model S estimates by that amount. I haven't gathered any data since EV Trip Planner added the P85D as an option, so they may be beating those estimates by less.

 

[Coiled]

Kudos @breser for collecting this data. I wonder if the speeds (35-40 mph) are too low to benefit very much from torque sleep.

In Tesla's range chart, there's no real difference between the 85D and P85D at 40 mph, but both are supposed to be ~6% better than the 85. So far I have yet to see either D get better range than an 85 in any test, at any speed, regardless of range mode. That's pretty disappointing.

 

[breser]

I'm more interested in why your efficiency didn't improve with range mode on. Do you think the temperature difference was enough to completely overshadow any efficiency gains from torque sleep?

I think there was an efficiency gain with range mode. You can see that clearly on the last chart.

Actually I just did some quick calculations from some of your numbers. You can do more if you like if you think I am mistaken, but it appears you actually -DID-- see an efficiency improvement from range mode.

The whole last chart is pretty much every number from the actual to the EVTripPlanner estimate compared and represented as a percentage. Not sure why you decided to redo it. Unfortunately you also redid it wrong (you used the formula ((actual-estimate)/actual) when you needed ((actual-estimate)/estimate), you've actually calculated the improvement if the actual was the estimate and the estimate was the actual).

- - - Updated - - -

Kudos @breser for collecting this data. I wonder if the speeds (35-40 mph) are too low to benefit very much from torque sleep.

In Tesla's range chart, there's no real difference between the 85D and P85D at 40 mph, but both are supposed to be ~6% better than the 85. So far I have yet to see either D get better range than an 85 in any test, at any speed, regardless of range mode. That's pretty disappointing.

I'm not sure. Keep in mind the speeds are just the average speeds. There are significant hunks that are 50-55 and significant hunks that are 25. There are of course quite a few stops in there. So it could just be the extra weight from the front motor/other changes (~110 lbs over the weight of my S85) is just eating up the gains in the slow parts that are made in the fast.

 

[Andyw2100]

I think there was an efficiency gain with range mode. You can see that clearly on the last chart.

The whole last chart is pretty much every number from the actual to the EVTripPlanner estimate compared and represented as a percentage. Not sure why you decided to redo it. Unfortunately you also redid it wrong (you used the formula ((actual-estimate)/actual) when you needed ((actual-estimate)/estimate), you've actually calculated the improvement if the actual was the estimate and the estimate was the actual).

I do see the efficiency improvement from range mode in the last chart. I have no idea what I was doing last night. I'll just blame it on being tired.

 

[vvanders]

Did our ~300 mi roundtrip. Sadly rain on the first and last leg threw off the numbers.

We did get a stretch with no rain, 55F outside, minimal climate(just front defrost when needed)

Evtrip has same leg at 53.8kwh/286 wh/mi. The route was a lot of mixed 40/55/60(Centralia wa to poulsbo wa via US3).

Also got this on the way back from home from Centralia

Pretty sure the Tesla was acting more like a boat in the rain at 389 wh/m. I could see the energy tab change if I drove offset in the lane out of the ruts.

Overall I haven't been able to see an noticeable improvement with range mode, I still plan to use it and do testing but it seems like the torque sleep efficiencies are well below weather based variations.

 

[breser]

So I haven't been posting much partly because I've been busy and partly because I've been lazy about posting the data I have collected. I still need to spend some time to post some of the collected data but I can say that range mode is a significant improvement in the 85D.

 

[breser]

So after nearly 7,000 miles I can same I'm pretty pleased. I'm getting pretty close to EPA rated (which would be 340 Wh/mile) on my rated. But i drove the car without range mode on for quite a while and the lifetime average is still creeping down. Range mode is a huge difference on the 85D. As you can see my 96.5 mile trip from the Burlington, WA supercharger today to home ended up being 306 Wh/mile. If I didn't live in a valley that I have to climb over the mountains to get in or out of I probably would do a lot better.

I've been pretty sloppy about keeping records. I have some of my trips in VisibleTesla. But I haven't been tracking temperature and a lot of other things.

I really need to find some time to do another decent road trip with a S85 owner and see how things compare now while controlling for weight.

 

[Khatsalano]

S85D with 7,200 miles at 325 wH/mi lifetime. Range mode usually brings it down to 310 wh/Mi or less. I don't drive fast or drive hard, but 90% of my driving on highway so my lifetime average is higher than someone doing 50/50 highway/city driving.

 

[Candleflame]

Changing tires is a bit far to go for a fairly casual comparison. We did try to control variables we could do reasonably but our real purpose was to head out to the new super charger in Coeur d'Alene and try it out.

My car uses probably 10% more fuel with winter tires if it's not cold enough. I think this is quite relevant.

 

[breser]

My car uses probably 10% more fuel with winter tires if it's not cold enough. I think this is quite relevant.

Neither vehicle had winter tires on and it wasn't cold enough for winter tires. The difference in tires was brand (S85 had the Goodyear Eagles and I had the Michelin Primacies) and wear level (S85 were nearly replacement, mine were new). I realize these are significant differences, if I hadn't realized that I wouldn't have pointed this out.

If someone wants to do a comparison with less differences in the tire area, I'm not stopping them, but so far nobody else has done this.

If you want a nearly perfect controlled test, use what Tesla is putting on the window stickers.

 

[breser]

Well I'm about to set off to Paradise at Mount Rainier by way of Longmire. Trip will be ~227.2 round trip miles, EV Trip Planner says round trip that it'd be 208 rated miles. I have alternate charging plans, but I'm going to try to do this round trip without charging. I think it's going to be a stretch for the vehicle.

 

[breser]

We made it on one charge. Did my first range charge, but I might have been able to do it without that (though I'd have very little buffer). We used range mode, though all rated mile numbers presented below are with it off. We had 3 adults. I drove at or below the speed limit. There were some areas I left it at 55 rather than going up to 60 and a hill that was right after a speed zone that I didn't accelerate up to highway speed to go up. I can't really calculate an average speed the way I usually do because we stopped and started several times. Trip is a little longer than planned because we made some side tracks (e.g. reflection lake) off the direct Paradise routing I'd planned.

237.4 miles
65.5 kWh
276 Wh/mile

Started with 100% charge, 268 rated miles.
Arrived at Paradise with 42% charge, 114 rated miles (car estimated 41%).
Ended with 13% charge, 35 rated miles (car estimated 9%).

If you take the 35 rated miles and add it to the 237.4 miles we did you come up with 272.4 miles, exceeding the 270 EPA rated range.

Watching the trip show the battery charge rising on our way down the mountain was highly entertaining.

To say that I'm highly pleased with the range and efficiency of the 85D is putting it mildly. I'd thought about this trip with the S85 but didn't get comfortable enough with the car to try it. If the 85D has lost range for me from the S85 I don't think I would have ever tried this. I actually did this with my mom in the car.

 

[Andyw2100]

We made it on one charge. ...

If you take the 35 rated miles and add it to the 237.4 miles we did you come up with 272.4 miles, exceeding the 270 EPA rated range.

Watching the trip show the battery charge rising on our way down the mountain was highly entertaining.

To say that I'm highly pleased with the range and efficiency of the 85D is putting it mildly. I'd thought about this trip with the S85 but didn't get comfortable enough with the car to try it. If the 85D has lost range for me from the S85 I don't think I would have ever tried this. I actually did this with my mom in the car.

Excellent post! Thanks!

 

[breser]

Started planning to do another side by side comparison with an S85. We're thinking somewhere closer. I'm planning to come up with a form to keep track of data so we will be more consistent about what we're tracking this time. If I can convince everyone to step on a scale and can come up with some ballast weight we'll try to account for any differences in passengers.

Just for fun here's my record lowest energy usage driving into work (for reference it's almost all highway only a few blocks either way off highway and 60-70 mph speed limits). Haven't really gotten close to doing that again (closest I've come is 300 Wh more).

 

[breser]

ThortsMD and I are traveling to Pendleton, OR tomorrow. This time we're going to do a better job keeping track of data!

 

[Matias]

Great!

 

[spottyq]

Thanks Breser for taking the time to do these comparisons !

Looking forward to your results.

 

[Andyw2100]

ThortsMD and I are traveling to Pendleton, OR tomorrow. This time we're going to do a better job keeping track of data!

So where are you stopping for the wheel swap?

 

[breser]

So where are you stopping for the wheel swap?

Haha. Actually didn't need to do that to get some interesting results. I need to write everything up but here's a spoiler. The 85D did better this time.