Friday, April 4, 2008

The Brake Pedal - I Don't Think It Is Your Friend

Yesterday night I drove my daughter and her friend to play practice. It
was rainy and wet with lots of twisty turns in the road on the back way
I took to the school. I did a lot of short accelerations and short
brakings as the turns came and hills went in order to maintain an
adequate flow of traffic.

As I was doing this, I was cringing in terror at how I was totally
torpedoing my fuel economy for this tank. Luckily, I had been able to
"hitch rides" three trips this week by drafting (but not too closely!)
behind tractor trailers and one day a tour bus.

When you drive, you press the gas pedal and make that engine work hard
to get your two-ton vehicle up to the speed you want it to be going.
That's a lot of inertia and kinetic energy that gets created there.
Once you're up to speed, it takes relatively little fuel to maintain
that speed. This is why it's so important to maintain speed. Every
time you slow down, you must use your engine to work hard to regain that
lost momentum. Going down hills is good for gaining speed, going up
hills is the opposite.

I like being stuck in heavy traffic going down hills. I can turn off
the motor and coast for a long time. Once I coasted for five minutes
with the motor off, but I digress.

When you're driving in traffic, consider what the cars ahead of you are
doing. If they are clearly going slower than you, make every effort to
ease up on the gas and let your speed decrease gradually so that you
match their speed before you reach their rear bumpers.

If you press that brake pedal, you lose all that kinetic energy and
momentum your engine worked so hard to create. Unless you're driving
one of those hybrids, of course, but for the sake of argument you're
losing that energy.

In order to get that speed back, you will press that gas pedal again,
using more gas to regain the speed you wanted to be going at before you
had to put on the brake. It's sort of like losing money with each tap
of the brakes.

Think of such things next time you're out there in traffic.

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