[Diesel_Dave]

Not to get the tread more sidetracked than it is, but the units of measure for emissions actually depend on how the certification takes place. It can be done on the engine, in which case the emissions are defined in brake specific values (e.g. g/kW-hr). It can also be done on the vehicle, in which case it's mass per distance (e.g. g/km). To make matters more complicated, the regs are sometimes a combination of engine certification and vehicle certification. Engine certification is also a combination of steady-state tests and standard transient cycles that are (supposedly) representative of the real world.

Anyway, I didn't really want a debate of what people feel SHOULD be the motivation for ecomodding--I asked what YOUR motivation was. :-)