John, you should not need to use engine braking in a car with disc brakes, which the Toyota has. Shifting down should be about being in the correct gear for the next corner, not about slowing down the car. If you need a source with more authority, here is racing coach Ross Bentley:
"What is the real reason for downshifting? Many drivers think it’s to use the engine to help slow the car down. Wrong again! The engine is meant to increase your speed, not decrease it. In fact, by using the engine to slow the car you can actually hinder accurate brake modulation and balance. Race drivers, and good street drivers, downshift during the approach to a corner simply to be in the proper gear at the optimum engine rpm range and to allow maximum acceleration out of the corner."
Ultimate Speed Secrets (p. 18). Motorbooks International. Kindle Edition.