Hi Caro,
I had a few minutes this morning and opened up my charting software and played with the Hot Wheels logo.
The best image I could come up with is a rather large knit chart. You'll need to use fingering weight yarn and get a gauge of 8 stitches and 10 rows per inch (which is what I get using fingering weight) for the picture to look it's best.
I've pared it down to a still big 122 stitches by 37 rows, so that means it's going to be at least 30.5 inches around. May be too big for your GS, but maybe not. The image will be about 3.7 inches tall. I tried smaller sizes, but it just didn't look right.
I put the image on my web site, but not on any pages. You'll find it here:
Leah