Does the RX400h have this EV Button option in Japan?.....I may be able to have a friend track down some japanese wiring schematics.

 

No it does not have EV button....

 

Toyota warns that use of the EV button could reduce fuel efficiency. Also, extreme swings in
SOC of NiMH batteries can cause damage or shorten the usable life of the battery. The system is
programmed to avoid over-charging or deep discharging, but some risk to the battery may exist. If you have a problem with your battery or Hybrid system or ECU and you have performed this modification, it may void your warranty and you could be responsible for thousands of dollars for repairs even if it can't be shown that the EV button was the cause of the damage.

 

one easy way I have found to keep going in electric mode, of course as mentioned if the catalytic converter is warm, the battery full, and the engine warmed up, is to use the left KW meter. it has the three sections of course, the blue for regenerative then a small section by the 0 with small horizontal black lines, then the gray section above that that shows the amount of electric power input demanded along with the engine.

if you are on a flat road, or a small incline with no traffic to hold up keep the KW needle in the area just above the blue regenerative section and right up to the 0 mark but still in the white area this will allow the maximum
electric power without the engine kicking in. and yes this corresponds to the speeds maceace quoted in his earlier post. hope this makes sense

 

as far as driving i posted this on another post but i believe when they set the mpg record they use pulse driving, just like you are talking about. use the electric to go as fast as you can then coast back down and repeat process. i guess trick is to burn ICE as short as possible and then coast and use electric to maintain.

and in terms of how fast you can go also depends on temperature outside. you'll coast much longer in 70 degree than 40 degrees. no heat or AC used