I just read the last few posts about tire noise and wonder if the Michelin Energy Savers that came on my 2015 SL are the cause of the faint whine I hear (I just assumed it was gear noise). The 2011 came with Bridgestone Ecopias which became progressively louder as the miles increased. I eventually replaced them with Michelin MXM4s which were much quieter (also better handling and traction under dry conditions) but they did reduce range a bit due to increased rolling resistance. I may look for the Dunlops when I need new tires.
Silver LEAF 2011 SL rear ended (totaled) by in-attentive driver 1/4/2015 at 50,422 miles
Silver LEAF 2015 SL purchased 2/7/2015; traded 8/10/2019 at 82,436 miles
White LEAF 2019 SL Plus purchased 8/10/2019