So I've started to drive my MY15 in D mode more frequently than B mode. I was always under the impression that B+Eco was the best for range and efficiency, but it seems like that's not the case.
My average efficiency in B+Eco was 4.7mi/kwh and my average efficiency in D+Eco was 4.9mi/kwh. I've been driving a nearly identical commute in D+Eco for 1000 miles, so I would assume that these numbers are pretty accurate and would indicate roughly a 4% benefit overall? My GOM readings have also improved, not that this is any real measure.
Here's what I'm thinking, D mode doesn't decelerate as aggressively and thus allows you to coast further. If you feather the throttle, you can actually coast in D mode with one green dot showing. Whereas if I use B mode, it decelerates so aggressively that I often have to use the throttle to speed up more frequently. I've also noticed that there's a very slight bit of added resistance when driving in B mode. If anyone wants to try this out, just drive at a standard speed in B mode, say 45mph and then shift into D mode. What I feel is perhaps a very slight gain in forward momentum, perhaps equivalent to 1-2 mph. Does anyone else notice this? Is this a deficiently of B mode, or is my car broken? What about any damage to the battery for the large amount of regen in B mode (equivalent to QC speeds?)
Lately I'm only using B mode if I know I'll be coming to a stop up ahead and can use the more aggressive regen, or if I'm going down a very steep hill.