v9990 is MSX
yamaha made the evaluation card as seen in the link that I put, then adjusted to the ascii specifications, so the V9990 is MSX.
The problem is that it was not mounted on a standard device but the card exists.
but this outrun I think it must be of msx2, to make such a game for V9990, better a hang-on with HUGE sprites, scaling and fullframe.
On the other hand, it makes the achievement even better if someone is able to produce something on the MSX hardware which people once thought was impossible. Getting the most out of our beloved MSX... That's what I like to see 
That's quite hypothetical of course. In some visual case, you simply know you've hit the walls already. And that's not even based on the VDP, but more based what you can do with simple block-copies with a top of 5KB per int, in fast mode. Or what you can do with fast sc1/2/4 tiles yet with limited color freedom. Scroll registers may have their value here and there, but certainly not everywhere.
In my opinion: Outrun on MSX2 will end up as a nice clone of Hyper Rally. So a player sprite, and an opponent sprite next to it (others are below or above), and no landscape features next to the road, only mountains at the horizon. If you're happy with that: fine. If you really want your landscape features, pillars, traffic signs 'n such (and different cars), then sooner or later you're going to hit the limits of the VDP. It's a mathematical certainty.
I didn't know I would spin a debate !
Thanks for all your messages.
What I would consider fun is squeezing that game out of the MSX2, and show things we would have thought impossible. In the end, I'm just someone who enjoys a good MSX technical challenge. My first challenge was to code a 3D road rendering engine as a proof-of-concept, and to show it was possible. That's done. As wolf_ underlined, it started as a demo. And it is a demo. Now, turning that demo into a game is the second challenge. And it's a bit more complicated.
I must say the V9990 is very tempting, because it removes instantly a lot of the limitations, and even opens new possibilities (125 multi-colored sprites is a whole lot ...). Cloning Outrun (or doing something similar) would be a lot easier with it.
I think, as Manuel suggested, that I will try both roads. After all, since I never coded for the V9990, it's a kind of new challenge for me, so I'll sure have some fun with that.
PS: 14 sprites for the roadside decor means I have to say goodbye to high traffic signs, palm trees, and in general, everything that would need more than 1 sprite in height. Remember that I use 32x32 sprites, so I need a minimum of 2 sprites per item, in order to smooth out the blockiness.
What I would consider fun is squeezing that game out of the MSX2, and show things we would have thought impossible. In the end, I'm just someone who enjoys a good MSX technical challenge.
Oh yeah... 
I understand the 'cheating' though. Your game would be special because something similar has never been made before on a standard msx2. If you make use of the v9990, the magic is gone.
Fully agree. As a Metalion pointed out earlier, this was an MSX2 project from the beginning so we should keep supporting it and try to overcome barriers together. I have to be honest, I'm not a coder and what I can say here maybe should not be taken into account but IMHO the challenge here and what would make this game so special (at least for me) would be an MSX2 version even with limitations. Okay the V9990 is great but the easy way and I suppose that the Amstrad development is the main motivation and the reference, I mean to "compete" on equal terms is the key. Remember that an Street Fighter clone with big players for MSX was an utopian dream and now we have Pointless Fighting.
The merit in F1 is not to win with Mercedes, Redbull or Ferrari but with McLaren, Renault, etc. 
