RX400h Notables

This is copied from rxhybridchat and is originally posted by dcarlq. The original article can be found here

• A closed-loop fuel system replaces the bladder tank used in the Prius. The system allows no flow path for the vapors to get out of the tank when the engine is turned off, using a tank closing valve that sits on top of the tank outlet andcloses the system from the vent standpoint anytime the engine is off, both at rest and idle stop. The evap canister is only used for refueling. In order to accommodate the extra pressures, the tank material has been increased to 2.0 mm from 0.8 mm. Refueling the 400h requires several steps as the vapors need to be bled from the system before the cap can be opened When the cap is released from inside the vehicle, it actuates an electric solenoid on the electronic fuel door. A series of messages come up on the IP, letting the driver know when it is safe to refuel. The tank holds 17.2 gallons and has a direct-read fuel gauge.
  
• Unlike Prius, which uses a hot water bottle to heat the intake manifold, the 400h has a different cold-start emission device that delays the start while it preheats the air/fuel ratio sensors. This allows the air/fuel ratio sensors to be active when the engine does start, reducing cold-start emissions. There is no need to wait on the engine as there is plenty of electric juice to launch the vehicle.
  
• The electric A/C compressor is slightly different than Prius'. The electric inverter is mounted inside the compressor itself. DC voltage is sent to the compressor and the onboard converter supplies AC to the system. It also has an electric water pump to pump block water to the heater core during engine-off operation in winter to provide heat to the cabin