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Is Model X's efficiency really this bad?
- Thread starter wk057
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- Driving Dynamics Model X
I though Regen braking allows you to transfer energy back to the battery and thereby save power. What is wrong with Regen braking?
Reciprocity
Active Member
Its great, but its not 100% efficient. Some energy is lost in the conversion from physical energy to electricity.
Sometimes it would be better to coast then to regen.
Well phrased, because the relationship is confounded with the addition of aerodynamic drag. I don't know the cutoff, but once you're up above 60mph, coasting and gaining speed can be worse than regen and maintaining speed.
There was an entire multi page thread devoted to trying to answer the coasting vs. regen question:
Regen vs. Coasting
I'm not sure I really agree with the conclusion though
Regen vs. Coasting
I'm not sure I really agree with the conclusion though
I did pretty much that exact same trip in August of last year. Raleigh to Tampa and back. The car was 3 days old at the time and my average consumption was around 340wh/mi. This is on a X90D with 20" stock wheels. I had myself and the 2 kids (young adults really) in the car with me and it was in the upper 90's the whole time and we had the climate control at 70 degrees. Now at almost 20k miles I'm still at around 340wh/mi lifetime average with no towing.
When I drove Raleigh to Michigan and back over Christmas it was quite a bit higher, more like 370-380wh/mi due to the cold. But that's truly the highest I've ever seen it unless I'm doing an acceleration demonstration for people
When I drove Raleigh to Michigan and back over Christmas it was quite a bit higher, more like 370-380wh/mi due to the cold. But that's truly the highest I've ever seen it unless I'm doing an acceleration demonstration for people
AndreyATC
Member
Not sure if he was going downhill, but that's not hard to beat in certain circumstances
This is on XP90DL with 22s
P.S. Now that the cold is over, my all-time average is dropping daily
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NikeWings
Active Member
Interesting comparison...........
I average ~ 100Wh/m more in my X than my S along the same route, driving under similar conditions. The S in mid-high 300s and the X in the mid-high 400s. 21s and 22s, and essentially the same cargo every weekend. I do not punch it off the light, but I do drive at a decent clip on the fwy. However, if I drop the AP below 70, its a huge difference. Sometimes I can drop below 300 in the S if I drop down to a steady 65.......and then ask why bother ?
I highly doubt you get that efficiency for the round trip. 300 Wh/mile is better than what Tesla predicts you should get in good conditions at steady 65 mph.
vrykolas
Member
Our X90D got as low as 290 What/mile driving from Dallas to Austin. Granted, temp was ~80F and about a 10mph tail wind. We drive at about 75 mph. I was really surprised.
Our lifetime average is 365 Wh/mile
Our lifetime average is 365 Wh/mile
Not lying. That's what I get on my daily commute. Down-hill to work, up-hill home. About a 800 ft altitude change. I got 200wh/mile on the way in this morning.
Of course, I can make it really bad if I drive hard. I'm just letting you know that the X is not always as bad as folks would make you believe.
Oh, no I am not suggesting you are. I was thinking maybe there is an error in your observations. I am delighted that good conditions can actually get such high efficiency
I made a 150 mile out-and-back trip yesterday from my home to my daughters house. The overall average for the entire trip was 291wh/mile. I used the TACC for most of the trip. The speeds ranged from 75mph on the interstate, 55mph on other highways and 50mph on some back-roads. I also kept to the speed limits as a test. These numbers jive with what I have seen over the short 2 months I have owned the vehicle (driven almost 6,000 miles so far). In other words, the vehicle is not as bad as you would be led to believe and the actual energy usage is highly impacted by the environment (driving style, vehicle speed, stop-and-go traffic, etc).
Remember that the 330 wh/mile is the EPA estimate derived from a defined mix of city and highway driving. Its use is to enable a comparison between vehicles, it is not a guarantee or an upper limit.
Remember that the 330 wh/mile is the EPA estimate derived from a defined mix of city and highway driving. Its use is to enable a comparison between vehicles, it is not a guarantee or an upper limit.
Whats interesting and what I like about your screen shot is - your roundtrip efficiency is 291 Wh/mile with your return trip at a higher consumption of 322 Wh/mile. This means your onward trip for 75 miles should have much less consumption than the overall 291 - or exactly 260 Wh/mile. Now thats too good for an SUV.
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