It may sound somewhat Orwellian, but people may be more open to this dashboard-mounted pollution monitor nowadays, especially if they've seen An Inconvenient Truth.
Japan-based Hino has developed the "DriveMaster Pro," which tracks a car's performance and compares it with the Japanese government's environmental recommendations. Akihabara News says the device, which uses an "ingenious array of sensors placed in your car," will "visually and verbally" indicate when driving patterns appear to counter anti-pollution guidelines. (It sounds a little like that talking radar detector.)
As useful as these gadgets may be, we're not sure if we want them yelling at us while we're behind the wheel. We have enough people in our lives who are doing that already.