2006 Lexus GS 300 Owners Manual - Page 650
2006 Lexus GS 300 Manual
Page 650 highlights
QUICK REFERENCE NOTE: Vehicles with the cruise control: When the cruise control is being used, even if you downshift from "D" or "6" (sixth range) to "5" (fifth range), or "D" or "5" (fifth range) to "4" (fourth range), engine braking will not be enabled because the cruise control is not cancelled. For vehicle speed reduction, see page 400. Vehicles with the dynamic radar cruise control: When the cruise control is being used in the conventional (fixed speed) cruise control mode or in the vehicle−to−vehicle distance control mode, even if you downshift from "D" or "6" (sixth range) to "5" (fifth range) or "D", or "5" (fifth range) to "4" (fourth range), engine braking will not be enabled because the cruise control is not cancelled. For vehicle speed reduction, see pages 423. 4