Step on it

Did you ever approach a stop light and have to decide whether or not to switch lanes because a line was shorter or did not contain a transport truck? Those of us who are in a hurry, and that seems to be the majority of us when we are in our automobiles, often slip over to the all-car lane in the expectation of saving a few nanoseconds on our trip. Lately, that has proven to be the wrong decision for me. Not that I am in a hurry, as we retired folk have far too much time on our hands. However, we do not want to delay all the busy people behind us.

Far too often, a line of transports can out-accelerate a line of cars, most often led by someone who is asleep at the switch or who thinks they are saving fuel by moving ever so slowly away from the start line. I say start line because some of these drivers seem to be waiting for a gun to go off to get them out of their lethargic state. A green or blinking green light is not enough to awaken them, get them out of idle, and into motion. As we creep away from the stop, puttering up to the posted speed, I wonder if we are really saving the environment. Meanwhile, the line of transport trucks is moving steadily away at an envious speed.

This may be a project for some young science-fair student, but there must be a formula to calculate the amount of fuel burned by a vehicle accelerating slowly to cruise speed and that of a vehicle that goes quickly to cruise speed. I can watch my in-car computer display the fuel consumption, noting the litres disappearing out the tailpipe until it settles down at cruising speed, and I know it is burning more fuel. However, I also know that I am going to reach my destination a little sooner and shut off the engine. If, and I suspect it is true, I consume less fuel moving quickly (not jack-rabbitting) to speed and shutting down sooner, then I, and all the cars following me, are saving the environment more than the driver who runs his engine for a longer (total trip) time.

There are no doubt a number of factors involved in this computation, such as when your car (or you) shifts gears, the optimum torque / engine rpm, weight, condition of your vehicle, etc, but there has to be an efficiency formula for every car. Those vehicles with a constant-velocity transmission may have an edge here, but there are still some of those drivers who refuse to step on it.

I expect that the airline companies have long ago found that it is best to get to altitude and speed quickly and then drop into cruise speed. Jet engines may behave differently, but it would be interesting to know if there are comparisons with piston engines. Perhaps our young scientists can look at the efficiency of four, six and eight-cylinder engines in the formula for creeping to speed vs quickly getting away from stop. Not that this would influence the people in huge SUVs, but if they knew they were helping us by accelerating properly, I am sure they would accommodate the rest of the driving public.

Once we know the answer to the quandary of stepping on it at stops, we can apply the same formula to longer trips. How much fuel did I save by getting to Toronto 15 minutes more quickly than by running my car for those 15 minutes at 100 kms? Sure, my average fuel may be 7.5 litres per 100 kilometres versus 8.0, but what was to the total consumption? Maybe if I had taken the New Math, I could calculate this. I await the answer.

In the meantime, think of how much less pollution there would be if every one of the millions of cars on the road could save a litre of gas a month. Maybe it is just a male thing, but imagine the satisfaction of being in a line of cars that can out-accelerate a line of transport trucks!