Or it may be a study from when he was finally being instructed to draw Sonic on-model. That's copied from the official model sheet, isn't it? EDIT: A bit modified, but it looks similar to it... kind of:
A full, colour, official version of the image in the OP definitely exists. I've compared it to the one IceKnight posted before.
This is an original pencil sketch and not a fax or mechanical copy. That would lead me to believe that Grew himself drew this but I can't be 100% sure.
That seems fairly consistent with what they were doing with Sonic the Comic around the mid-90s. p.s. please please please scan these things one day
Awww, I was expecting to see some info about the next Sonic game. So, umm, yeah, that looks cool. I really like Classic Sonic's Japanese design. It's much better than his western design.
Greg Martin was an illustrator here in the USA. To the other poster there is no way this has anthing to do with the Archie Comic.
From the art assets DVD we have right here on Retro... Is Greg's drawing just a copy to help him better understand the style?
Richard Elson's Sonic the Comic art was my first thought too. I guess he must have had access to the same material?