Helmet, neckerchief, shirt and gloves (from episodes 1-3):
More screencaps below the jump:
Speed’s hair and eyebrow color seems to change depending on the scene; either black or dark brown
Pants legs, shoes & socks:
Note that the ‘vents’ in the pants legs are only on the exterior sides of the legs. More evidence of this is shown in the model sheet below.
Composite intro screencaps: