Cozy Corner

This morning, I had a question: is the route I drive to work, which is a straight line across several hills, with lots of stoplights (which makes fuel efficiency painful) cheaper in fuel than a more roundabout approach which crossed no hills?

Now, I assumed that my fuel efficiency is poor because of the hills and stoplights; I normally average about 22 mpg on that route, driving a hybrid SUV. Generally, stopping at the bottom of a hill (and burning your momentum) isn't a way to get good fuel efficiency. So I decided I'd measure the fuel efficiency today, and then take a more circuitous route in a couple of days. But in measuring it today, I decided that maybe the problem has been my driving; not the hills.

You see, there are two ways to drive a hybrid. One way is to treat it like any other car, and quickly accelerate and decelerate. At the opposite end of the extreme is the obnoxious hybrid driver mode - slow acceleration; lots of coasting, and never really getting to the top speed you might otherwise. So today, I drove closer to the obnoxious end of that spectrum, but within reason. And what I noticed was interesting. I have a 4.7 mile commute, and the first mile and a half - going to work *and * returning - sucked: about 16 mpg. The combustion engine just wouldn't turn off. The remaining 3 miles, on the other hand, averaged in the mid-30s for fuel efficiency; I netted 25.7 mpg on the way to work, and 28.7 on the way home (27.1 average).

Clearly, my fuel efficiency is getting killed by that first five minute interval while the engine runs to warm itself up. So my next two experiments are going to be different than the circuitous route. First, I'm going to let the car idle until the combustion engine shuts off, and see if the cost of letting the engine idle is lower than the cost of having the engine run while driving (logically, it isn't, but it's a necessary experiment). Second, if the engine is going to run anyway, I should attempt a trip where I try to cover as much distance as possible in the first 5 minutes of my commute, when I have an inefficiency added in, and then try to be efficient once the combustion engine stabilizes.

More on this later. But an interesting time. I think the biggest drawback is that focusing on efficient driving reduces my relaxation time while driving.