Consumer Reports - Winter chills limit range of the Tesla Model S electric car

[RDoc]

The Rav4, at over 4000 pounds, does significantly better on the freeway at 65mph than around town.

In the LEAF, I could easily match the 4 miles per kWh (250w per mile) at 65mph (without a heater) on nice days that I could also do around town. On the Rav4, it's not even close; I average 2.7 (370w per mile) around town and 3.4 (295w per mile), again, without heater on nice days at 65mph.

That's very interesting, thanks for the info.

Perhaps what's going on is that the regen on the Leaf is a much larger part of the braking power than it is in the heavier cars. That is, relative to the Leaf, the weight on the Rav4 and S has increased more than the regen power. The result would be that more energy is dumped into the brakes than into the battery on the heavier cars since the battery just can't absorb it all. On the highway, more of any deceleration needed can be done by the regen, so not using the brakes more than makes up for the drag losses at higher speed.

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Actually the power to maintain speed is based on the cube of the speed so it's even worse.

From http://en.wikipedia.org/wiki/Drag_(physics)#Power

Right, but the distance covered is proportional to velocity so while the power goes up with the cube of the velocity, the energy used per mile only goes up with the square. I think more people are interested in KWh/mile than KWh/hour.

 

[100thMonkey]

you and anyone who has some savvy and knowledge of this topic will get that distinction but I think the subtleties get lost on the general public. it's amazing how many folks know about the Broder article, I've already heard someone say that the Consumer Report's article confirmed what Broder was saying, not disproved it. The fortunate thing with consumer reports is that their testing is long and thorough, so there is still more time for them to catch their oversights... there is also still time for Tesla to send out an addendum to the manual which includes cold whether protocols, in time for Consumer Reports to get them and incorporate them into their testing.

I agree that its not a perfect article. But he was pretty clear that he was simulating a short (~90 mile) trip out of town, in the cold, to a location that didn't have a charging station. In fact, its pretty obvious he structured the entire article to address the bogus NY Times article. The bottom line in his testing is that a full standard charge (which he explains, while contrasting it to a range charge) would allow the car to travel ~180 miles despite an overnight stay (in the cold) without access to an outlet.

Consider: Broder states that he left Milford with 185 "rated" miles, stayed at a hotel overnight, and failed to make it back to Milford while describing all of the stupid things he did to try to mitigate his problem (whether advised by Tesla or not, they were stupid). Consumer Reports went through the trouble to simulate that trip, and then explained how the overnight range loss is partly illusory and how you should just drive through it.

Consumer Reports even made the effort to debunk the use of "Rated Range" that Broder relies upon, and gives an extensive discussion about how accurate "Projected" range was in this circumstance. This article was a head to toes takedown of Broder.

Sure, there are nits, and Consumer Reports certainly isn't representative of the state of the art when it comes to cold weather driving in the Model S, but their review clearly demonstrates how the Model S actually performs on the trip that Broder failed at. I'd suggest sending them a note with your observations so they can attempt to improve upon their performance. Frankly, from what I've read they are one of the few media organizations which made a real attempt to refute Broder and establish a realistic baseline for the particular conditions that Broder screwed up with.

 

[CanuckS#69]

One of the things that strikes me as odd with many of these reviews is that the journalists don't seem to have gotten the simple walk through that all of us owners got at delivery, explaining how the car works and how it differs from an ICE. I'd even venture to say that at minimum Tesla needs to deliver the cars to journalists locked into Range Mode to avoid all of these EPA range fallacies. While there are things to learn about driving a Tesla, it isn't really all that difficult to understand and is fact much like owning a smartphone, which I'd assume most journalists do.

 

[EarlyAdopter]

The Engadget author mentioned he got a walkthrough of the car before Tesla handed over the key, including efficiency tips. I suspect all reviewers do, but many choose to ignore it.

Tesla vs. The Times: What one review means for the future of auto news

"It's in this last point that the question of malicious intent can be most clearly raised. It's quite easy to mistakenly charge the car well short of maximum. In fact, it's the default setting. A "standard" charge in the Model S is about 90 percent battery capacity. You have to manually toggle the car to "Max Range" (as shown in the photo above) if you want 100 percent. This is because fully charging the cells every time decreases the ultimate longevity of the battery pack, so you're advised to use this only when you're planning on going a long distance. The Tesla rep who briefed me before my review of the Model S made this distinction abundantly clear. I'm inclined to believe they did the same for Mr. Broder."​