For your consideration,
In the original article...
Stalled on the E.V. Highway - NYTimes.com
... Mr. Broder made claims about setting the cruise control at 54 mph.
In the subsequent rebuttal...
A Most Peculiar Test Drive | Blog | Tesla Motors
... Mr. Musk counter-claims that the vehicle speed was between 65 and 81 mph.
In the follow-up...
That Tesla Data: What It Says and What It Doesnt - NYTimes.com
... Mr. Broder asserts:
"Certainly, and as Tesla’s logs clearly show, much of my driving was at or well below the 65 m.p.h. speed limit, with only a single momentary spike above 80. Most drivers are aware that cars can speed up, even sometimes when cruise control is engaged, on downhill stretches."
These are the public statements. Let's take them in aggregate and assuming all parties are being honest relative to their recollections.
With that approach in mind, let's say that Mr. Broder did in fact set the cruise control at 54 mph. Let's further assume that the Tesla logs are correct and that Mr. Musk's representation of those logs is accurate. Let's further assume that some mechanical failure or timing mixup in Mr. Broder's notes accounts for the 80mph speed while the vehicle was set on cruise control.
This still leaves the vehicle cruise control being set at 54 mph yet the vehicle going at least 65 mph.
From this we can assert that the cruise control was off by 11 mph -- for an extended period -- not just momentarily. If it was truly off by that much, then Mr. Broder is negligent as a driver for not disabling cruise control and returning his speed to the desired level manually. Further, he would be off-the-mark as a reporter for not reporting this significant failure in the cruise control system.
Ignoring these failures as a driver and as a reviewer on Mr. Broder's part, let's evaluate the vehicle.
Does the Model S stray that far from the set cruise control? No it does not. I've logged 2500+ miles on the vehicle since taking delivery mid-November. It never strays more than 1mph from the set speed. I've even done a specific test with Regen set to Low on the vehicle to see if it has any impact on this experience. It does not.
I've posted about some of my testing of the Model S cruise control behavior at the link below.
NYT article: Stalled on the EV Highway - Page 98
Thanks for your time and your diligence in reports the facts faithfully,
- Brian
P.S. I'm also publishing this e-mail on the same thread in that forum. I'd be happy to publish a response in kind if you have a message you'd like to express in that venue.