Most of my first thoughts have already been addressed.
I'm not sure how coherent this will be, but bear with me...
When I was in early elementary school, after I was tested and placed as GT (gifted and talented for those from other areas), we would be pulled out of class periodically for special programs/events that the other kids wouldn't.
It allowed us to learn what the other kids were, plus explore some additional areas in ways not allowed in a traditional classroom - more creatively and in more depth. I remember one time we put together a "newspaper" - we wrote the stories (all fiction), the advertisements, the comics, the crossword - all of it. Another time we learned about the 8 (7?) ancient wonders of the world, another time it was a lesser-known sport - for both of these we were given a the topic and allowed to research and build a diorama/poster board, etc. with the information we learned. I remember those GT activities more than I remember almost anything else about my early childhood years. It definitely instilled a love of learning.
I'm not sure if any school is still doing this - you may want to check. It sounds like your son is at a pretty progressive school. It also may still not appeal to your son - but being pulled out as "special" might give him a bit of motivation.
As others have suggested, home schooling might be a good option. However, it's not possible for many of us. There's the idea of "unschooling"?? Where you don't have set lesson plans, but you take his passions and turn them into lessons. For example, Beyblades - use that to discuss inventions, patents, toy research and production, focus groups, etc. Or, you use it to teach about gravity, physics, etc.
He also sounds mechanically gifted. He may be more of a kinetic learner - he needs to DO something rather than be told or read about it. Obviously, in order to prove learning to the school's and government's satisfaction, he'll need to deal with SOME non-kinetic activities and assignments, but if they were fewer and his opportunities to get hands-ons with something were increased, it might not be so much of a struggle.
But - I wanted to add - it sounds like your son has an INCREDIBLE teacher. Talk her up to her principal - they get so little positive recognition.