A groaning sound might be a bearing, does it do it with both right and left turns? Does speed increase the sound during the turns? If you have AWD and the sound is present on both right and left turns, it could be a problem with the differential. There has been a history of noise coming from the rear suspension during turns in the FEH/MMH also. I never had that problem with my '05 FEH so I can't describe the noise.

Regenerative brakes come from the Traction Motor inside the transaxle (eCVT). The brakes are normal Disc brakes on the rear and the front wheel are what is used to turn the traction motor into a generator upon deceleration or applying the brake pedal. In other words regenerative brakes is when the traction motor is turned into a generator to slow you down in addition to the actual brake pads.

If your premium gas does not contain ethanol, it might be better than E-10 to use. All regular and premium fuels here in Florida contains ethanol.