Originally Posted by Technic
The only think that we need to know about Audi is that they sell less vehicles as a brand than the 3-Series alone.
I take it you are talking about sales in the US?
If so then I whole-heartedly agree with you, Audi isn't that strong sales wise to what BMW are doing, but then again BMW are only buying business through selling their products at a greatly reduced price. In fact if they didn't do this then as a company BMW sales worldwide would be far smaller than Audi which is only a branch of parent company VW. So while it's correct to say what you did there are commerical reason for this fact.
As for the differences between both brands and which is better, I don't believe either brand is better than the other and it's always down to personal opinion.