Chapter 9 | 533Park in the Garage
The engine of a car parked in a garage overnight is warmer the next morn-
ing. This reduces the problems associated with the warming-up period such
as starting, excessive fuel consumption, and environmental pollution. In hot
weather, a garage blocks the direct sunlight and reduces the need for air-
conditioning.
Start the Car Properly and Avoid Extended Idling
With today’s cars, it is not necessary to prime the engine first by pumping the
accelerator pedal repeatedly before starting. This only wastes fuel. Warming
up the engine isn’t necessary either. Keep in mind that an idling engine
wastes fuel and pollutes the environment. Don’t race a cold engine to warm it
up. An engine warms up faster on the road under a light load, and the cat-
alytic converter begins to function sooner. Start driving as soon as the engine
is started, but avoid rapid acceleration and highway driving before the engine
and thus the oil fully warms up to prevent engine wear.
In cold weather, the warm-up period is much longer, the fuel consumption
during warm-up is much higher, and the exhaust emissions are much larger.
At 20°C, for example, a car needs to be driven at least 3 miles to warm up
fully. A gasoline engine uses up to 50 percent more fuel during warm-up
than it does after it is warmed up. Exhaust emissions from a cold engine dur-
ing warm-up are much higher since the catalytic converters do not function
properly before reaching their normal operating temperature of about 390°C.
Don’t Carry Unnecessary Weight in or on the Vehicle
Remove any snow or ice from the vehicle, and avoid carrying unneeded
items, especially heavy ones (such as snow chains, old tires, books) in the
passenger compartment, trunk, or the cargo area of the vehicle (Fig. 9–60).
This wastes fuel since it requires extra fuel to carry around the extra weight.
An extra 100 lbm decreases fuel economy of a car by about 1–2 percent.
Some people find it convenient to use a roof rack or carrier for additional
cargo space. However, if you must carry some extra items, place them
inside the vehicle rather than on roof racks to reduce drag. Any snow that
accumulates on a vehicle and distorts its shape must be removed for the
same reason. A loaded roof rack can increase fuel consumption by up to
5 percent in highway driving. Even the most streamlined empty rack
increases aerodynamic drag and thus fuel consumption. Therefore, the roof
rack should be removed when it is no longer needed.
Keep Tires Inflated to the Recommended Maximum Pressure
Keeping the tires inflated properly is one of the easiest and most important
things one can do to improve fuel economy. If a range is recommended by the
manufacturer, the higher pressure should be used to maximize fuel efficiency.
Tire pressure should be checked when the tire is cold since tire pressure
changes with temperature (it increases by 1 psi for every 10°F rise in temper-
ature due to a rise in ambient temperature or just road friction). Underinflated
tires run hot and jeopardize safety, cause the tires to wear prematurely, affect
FIGURE 9–60
A loaded roof rack can increase fuel
consumption by up to 5 percent in
highway driving.