Audi's unveiling of the new A3, showing that the car formerly known as the little hatchback of the family has grown into a sedan, continues one of the surest trends in the industry: each generation of a given car will be larger than the previous one, eventually requiring a new smaller model to be introduced in its place. So it went with BMW as well, where the 3-series gradually grew to the size of the former 5-series and the 1-series had to be introduced lest they abandon the compact market entirely. No doubt the A3 will be an outstanding little sedan, lightweight and sporty in a classic A4 kind of way, but there are a couple of reasons this trend of size escalation need not continue. First, the message is finally out about efficiency and handling; with some of the most appealing cars on the market being the smallest consumers would seem to at least be ready to accept status quo in size from one model year to the next (if not actual deflation). And second, well, you're going to run out of small numbers. A few years from now we really don't need to be driving around in our BMW -135is or Audi A0s. Something has to give.