GLE 450e Plug In-Hybrid. Car went into âTurtle Modeâ on Saturday March 8th for no known reason. Turtle Light and Check Engine warning lights came on and there was a warning message âSignificant Reduction in Powerâ. My understanding this is a vehicle initiated precaution when something triggers the vehicle to go into reduced power mode. This all happened after the car had been driven on the highway for about 2.5 hours. It was running in gas engine mode since the battery power had been off for 1.5hrs. It was also about 30F in VT that day. The turtle mode came on as soon as we exited the highway. The vehicle was drivable, but there was almost no acceleration from 0-20mph. Once the car was above 25 mph and 2k RPMâs it could run 40-60mph but it had no brisk acceleration. When we stopped at lights, the poor acceleration continued all the way to our destination (so it ran 1.5 hours in Turtle Mode). But this is certainly a flow of traffic issue as the car pulls away from stops at a very slow and deliberate speed forcing other drivers to alter their driving. When we parked the car at our destination both the Turtle warning light and check engine light were still illuminated. Several hours later for our 4-hour return trip back from VT, when we started the car the check engine light was on but the Turtle warning indicator was off. The car appeared to run normally in ICE mode but we didnât push it hard. Towards the end of our trip after we stopped for gas, the check engine light stayed off.