I'd say I forget to shift back to D from a stop about 5% of the time also Tom. When I try to shift to N for the coast, that's when I catch myself and shift to D and then to N. Driving in L under 50mph (around town) will decrease your MPG by an average of 5.1mpg.
"Important: Many of us drive in low gear ("L") thinking we are in the same state as drive ("D"). During my tests, I accidentally left the shifter in "L" and came up with astounding results. It appears that "L" at below 50 mph, there is still regenerative braking occurring while in cruise control. This must also be the case while not in cruise control. The result I was getting was a 5.1 MPG reduction at 30 mph while in the "L" position over the "D" position. At 40 mph, I was getting a 4.1 mph reduction in "L" over the "D" position. To sum it up, I will no longer be using the "L" position in the steady state cruising mode. In addition, I believe that using "L" in EV mode may reduce fuel efficiency. This is sort of like saying the "L" position causes an accelerate or brake (regen) "L" mode, instead of an accelerate and (light regen)"D" coast mode. Based on these test, I recommend using "L" for going EV and charging the battery only. Driving only in "L" will reduce your FE"
Thanks, I won't feel quite so bad when I forget to shift back to D next time. I had a suspicion that driving in L was not as efficient. I have been monitoring regeneration lately with the AMP xgauge. The negative amps for regeneration is much more informative than just seeing the up arrow above the battery display. L is quite aggressive. I like to use L when it is safe to do so while gliding to a stop since It is very efficient at slowing me down. When I use the brake for slowing to a stop while in D it is amazing how I often can't quite get to 100% on my brake score. I figure I press a little too hard when I first start braking.