Right but even the 'diesel in cruise' is still less common than you'd think. There are hills up and down, there's passing, there are bridges, headwinds and tail

Right but even the 'diesel in cruise' is still less common than you'd think. There are hills up and down, there's passing, there are bridges, headwinds and tailwinds, etc. Required power is different if you're fully loaded vs partially vs empty vs no trailer. Even on interstates there are towns every 50-100mi that have their own traffic and thus non-cruise speeds. If the exception to cruise is only 0.1% then I agree it's dumb to consider. If it's 10% or more and the emissions during non cruise are significantly worse, it could end up accounting for 30-40% of total emissions instead of just 10%