I agree with Jean and James, this is a field that is going to go ballistic over the coming years. Just three years ago I used to sub out diag. jobs that were coming in to a member of this site, he used AD which at that time was a good generic tool,which seems to have had a bit of a lapse recently from what I read but the only way forward on this subject is to specialise in a few makes, I can fix the less complex jobs that only a few months ago were beyond me but my aftermarket scanners are playing a rapid catch up game which allows me to do repairs that I could not have done 6 months ago. CAN is the big thing now,I cringe when I get a CAN fault logged although it can be due to a very simple cause, flat battery for example,back to the original question from Mike, I probably think not, multi-makes are too diverse and the cost is prohibitive for all those dealer tools for an average small business.