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[Skidz]

If you look at energy needed to overcome engine weight and such, the only thing that matters in the comparison of the S vs the SR is the rotor of the motor. Since they are both IPM, the weight won't really be different I guess. And since the rest of the drive train is virtually identical (The stator mass might differ a bit) the opposing forces when accelerating or keeping speed will be the same, hence the same energy is used. So only the added weight of the static part of the motor and the added weight in the rotor together with the controller are different...
For combustion engines, my old teacher told us that a four-stroke uses around 5% of it's mechanical output power to drive the valves. A small 40kW engine would then need only 2kW to drive the valves, but a big 375kW engine would use 18,75kW energy just to idle! This energy comes from the fuel, so the mileage of an 8-cylinder would be way worse than a 3-cylinder.

And that's the beauty of electrical drive systems. If you need 5kW to go 50mph, the system uses 5kW. No more, no less. No choosing the right gear, no pesky valves to run, no generators, no ignition systems...

[togo]

That's a good way to put it, yes.

And yes, I think the more powerful controller is the main difference, you may be right about the motor connectors.

[Rugby4life]

> So much affects range; acceleration, regen, ...

Indeed, Regen is a big difference between the S and the SR.  The SR has a more powerful controller, so indeed, the same regen setting is stonger on an SR than on an S, and you do feel it kick in more strongly and more power goes back to the battery.  So you put out power faster but you get to the same top speed, and when you slow, you get more of it back.  Not much, but it seems to net out in my case.  Also with the more powerful motor and the more powerful regen, the hills seem to net out better, and the extra weight of a passenger much less than you'd expect.

I finally completed my semi-scientific range comparisons of the 2017 FXS, DS 13.0 and the SR 13.0 on the same route simulating my local usage. Each bike was charged to 100% and left on the charge overnight to complete cell balancing. Max range of the FXS was 42 miles (mostly in eco mode) rolling back into the dealership with 0% left. The DS completed 85 miles (2 to 1 sport/eco modes) with 2% left. The SR completed 91 miles (mostly sport mode) with 9% left. It was surprising that the bike with the most powerful motor, ridden most aggressively would return the best mileage. Your results may vary since I'm 300+ lbs and present a rather large aerodynamic cross-section. Basically, I replicate riding 2 up. My take is that the "R" motor allowed me to accelerate to cruising speed much quicker, allowing me to roll off the throttle sooner. Also the regen was much stronger, harvesting much more energy back to the battery.
As a side note, on the SR, I set up the custom mode with full top speed, full torque, full braking regen, and 0% coasting regen. My thought was that when I was coasting on a downgrade or as I was approaching an intersection I would be consuming no electrons and gaining free miles. After a 10 mile loop in sport and then in custom modes, I got marginally better watt hrs per mile in sport mode (about 1%). I guess regen is a larger contributor than I thought. BTW, I'm sold on the SR, just looking for one with a power tank... or maybe a 2018 depending on what upgrades they announce next week.

[Lenny]

Coasting is always more efficient than regen if you ride with care. With coasting you can use up to 100% of the kinetic energy you have, with regen only up to ~60%. However regen is still better than turning kinetic energy into pure heat with the brakes.

Don't forget the DS tires, which make a huge difference. If there was also a windshield involved that makes another 5% difference.

In contrast with ICE engines, electric motors aren't necessarily less efficient just because they have more peak power, because peak power mostly makes temporary use of thermal reserves which are not available forever (a Zero motor will do thermal throttling if you push it too hard).