[Old Tele man]

...since we're much closer to MISSOURI here in USA than you are there in AUSTRALIA, you'll have to endulge us and SHOW us (well, me for one) where and how you "...gained a fuel economy improvement of 15 per cent on a particular urban route."

...for instance, I have no idea whatsoever of what you specifically mean by "urban route." I'm sure what I perceive to be "urban" here in Arizona maybe be similar, but not the same, as what you mean. And, what were the speeds and times-to-speed and coastings that comprised your particular urban route (what made it particular?).

...and "negative" shouldn't be confused with "skeptical." Hence, the Americanism: "...I'm from Missouri, so you'll have to SHOW me."