Traverse City, Michigan hosted two conferences on the auto industry last week: one that I read about, and one that I attended.

The one that I read about laid bare differences among regulators and the auto industry about the possibility of reaching ambitious goals for reducing greenhouse gas emissions, commonly expressed in miles per gallon figures.

The one I attended revealed some interesting, and possibly productive, areas of agreement among regulators and the auto industry as to how we might work together to achieve our policy goals.

I hesitate to get bogged down into a discussion of whether we should require automakers to average 50 or 54 or 154 miles per gallon by a certain date, because so many of those projections depend on how consumers behave: whether they’ll buy SUVs or small cars, V-6 engines or hybrids, vehicles with one row or three, how they’ll react to the price of gas, and so on. And consumers are notoriously immune from the influence of government regulators. They tend to make up their own minds. And let’s also note that the numbers are easily misinterpreted. The miles per gallon number doesn’t tell us about the advanced technologies -- battery electric vehicles, fuel cell vehicles, plug-in hybrids – that are available right now. It doesn’t tell us what the engineers are able to produce; it tells us what people are actually buying.

Which is why I found it interesting that there was general agreement that we have to do more to enlist the consumer in achieving greenhouse gas reduction goals. That means a number of things: building the infrastructure to support a sustainable personal transportation model; eliminating regulatory barriers to innovation that could give the consumer cleaner, and cheaper, choices; and moving the discussion beyond the numbers game and beyond 2025 to see what each of us can do to lower emissions at the lowest cost.

These are topics that are going to keep coming up, and we’ll be offering more thoughts on them in the weeks and months ahead.