Is there a difference in driving in D vs L on the highway? I usually drive in the city mostly, so the rare times I get on the highway, I stay in L. But I wonder if driving in D is more efficient on the highway.
There's no difference if you drive the same way - i.e., at a constant speed. Some people complain that it's harder to maintain a constant speed in L mode because of the higher regen and because the smaller range of pedal travel (because in "L" the first bit of pedal travel is for regen) magnifies small pedal movements a bit. I always drive in L mode and haven't found it to be a problem. And I generally use cruise control on the highway anyway, in which case it's a moot point.
I leave mine in L and use the cruise control on the highway. In effect, there would be no difference at all. I do like the idea that once I cancel the cruise, be it for slowed traffic ahead or exiting, it immediately begins that slowdown that I've become used to.