are these works final ? do they work as replacements for the releases on mm2x.com ?
No, they don't. This is either for educational purposes or for developers preferably. Average MM2 users could try these cars and leave spontaneous feedback. That would be greatly appreciated, and credits will be given in the final releases as well.
will you leave an eta (estimated time available for the releasing the beta and wip's) here or at mm2x.com ?
ETAs are impossible to give particularly in this field because of the reason that us MM series DEVs use ancient softwares for making projects and no one knows what/when we might hit a snag. There's never a definite time or deadline, so it's a NoNo from me.
I'm a developer (mm series or any other) and i feel you've used my work without my permission.