06 Aug 07
BP's Alex Cutler: facts at his fingertips
BP engineer Alex Cutler had plenty of suggestions, but it took a computer graph to really make me sit up (and that has to be a first). The most arresting graph showed my consumption in millilitres per second (m/s), alongside that of the Economy King's. Only twice did his spike past the four m/s line. Mine did so 15 times. I even broke the 6m/s second line once. That's the equivalent of drinking a can of Coke in less than a minute, and about as healthy.
'Within a certain band an engine is calibrated for the emissions test. Anything outside of it's generally tuned for performance,' Cutler told me. In other words, if I raise the revs beyond those reached in the rather sedate test standards, there could be a disproportionate fuel penalty.
Graphs reveal the awful truth
I'm shown another graph and this time I spot about a mile during which the Economy King managed to use absolutely no fuel. Zero. I ask about this. From the highest point on the Millbrook course, I'm told, he coasted all the way down, gathering enough momentum to crest a couple of smaller hills.
Except coast is the wrong word. 'You leave it in gear, and lift off the throttle. The injectors actually turn off, using no fuel at all,' explains Cutler. In gear, the car's momentum keeps the engine turning, but bung it in neutral and the car thinks it's idling, so asks for fuel. This canny hill driving he calls 'momentum management'.
