why buy a macro lens just buy some tubes everyone seems to be focusing on macro and really it more close up than macro so tubes will be plenty, to photograph actual racing he is going to need a long lens that performs...
and really a 60D or 6D af for tracking race cars? F1 cars? ummmm No.
For the OP stated uses the best would be to
A) accept $2000 isnt enough and it will over run
B) get a 70D the AF will be better than going for anything with a crappy 9 pt AF
C) look for a used 15-85 IS to save some bucks (I got one for my parents for $400) new they are about $800 i think
D) get a tamron 150-600
and E) get some AF tubes for close up work with the 15-85
probably grab a $100 50 f1.8 mk2 for now for some wide apperture fun
get a tripod later the 150-600 can be handheld easily enough.
Formula 1 cars go up to 200 miles per hour... or at least I think they do in my video games. But the question is how far will the photographer be from the subject? My guess is that he would be in the stands... so lets say 20 meters is as close as he'll ever get to the vehicles in motion.
Per a dof calculator (@ f/5.6):
Subject distance 65 ft
Depth of field
Near limit 61 ft
Far limit 69.5 ft
Total 8.5 ft
So we aren't talking about shallow depth of fields with a speedy adjustment by the lens to keep focus. I think the 60D, 7D, or even a 50D could keep pace with a car going 200 mph when you are that far away. Heck... my old Canon XS can probably do an adequate job... though I don't recall if the XS has an AI servo mode...
Also... when you are that type of distance... the perceived added reach of a crop sensor along with a 1.4x teleconvertor will get you close to the action...
I know we as a group will praise full frame... and it is nice... very nice... super nice... I don't want to undersell it... but crop isn't that bad. In good light, I contend it is difficult to tell the difference. @ higher isos... ok... crop is noticeably worse... but the races will take place outdoors... sunny... cloudy... depends on the desired shutter speed. 1/6000 will limit the blur only to the tires, but at 1/200, presuming he is panning, will blur the background as a result of the camera movement... So f/2.8 isn't that necessary.
I think the 100 non L is a good option for the macro work... but the fact of the matter is that there is more than one way to skin a cat... which is a stupid saying... I think a more apropos phrase is there is more than one way to get a woman into bed.
And most of the options discussed will be adequate for the tasks listed.