More information on the 2000 ES300 VVT-i Ignition Coil fitment:

These are compatible with the 2000 ES300 with VVT-i ONLY. These will not fit the non VVT-i 2000 ES300. The plastic engine cover should say "VVT-i" in red when you open the hood.

If there is no engine cover, take a look at the front three coils on the car. They should not have spark plug wires connected to them. The non VVT-i uses 3 ignition coils in the front with spark plug wires connected to them.

Definition of VVT-i: Variable Valve Timing Intelligence