Chapter 1 The Automobile 7
General Vehicle Specifi cations
The following section describes common vehicle
specifi cations. Manufacturers generally publish
these specifi cations for each model they produce.
Vehicle curb weight is the total weight of the vehi-
cle with a full tank of gas and no driver. Vehicle curb
weights vary.
Generally, pickup trucks and SUVs are the heavi-
est vehicles and weigh two and a half tons. Full-size
cars, station wagons, and full-size vans weigh about
two tons. Compact cars have a low curb weight of
about 3000 lbs. Small sports cars and micro cars are
the lightest passenger vehicles, weighing in at about
a ton.
Vehicle weight distribution is a measurement of
how much force is pushing down on the front and
rear tires of the vehicle. An ideal weight distribu-
tion for economy and cornering ability (ability to
turn a corner while maintaining directional stabil-
ity) is 50/50, or 50% front and 50% rear, as is found
on many high-performance sports cars. Front-wheel
drive vehicles have about a 70% front and 30% rear
weight distribution for good traction.
Vehicle wheelbase is the distance from the center-
line of the front wheels to the centerline of the rear
wheels. A typical wheelbase for a full-size car might
be 100″ (254 cm) for a small, compact car and up to
150″ (381 cm) for a full-size pickup truck.
Track width is the distance between the center-
lines of the two wheels on the same axle (right and
left front wheels or left and right rear wheels). The
trend is to make vehicles wider so they can corner
more quickly without a rollover accident. A typical
track width might be 62″ (157 cm) at the front axle
and 64″ (163 cm) at the rear axle.
Vehicle length is a measurement from the outermost
point on the front bumper to the outermost point on the
rear bumpers. Vehicle width is the distance between
the two widest points from the right to left sides of the
body measured perpendicular to the vehicle’s center-
line. Vehicle height is measured from the ground to the
highest point on the roofl ine. Refer to Figure 1-5.
Vehicle Size
A full-size car is capable of carrying four or fi ve
adults. It usually has four doors and is rear- or
all-wheel drive with a relatively large engine. Since
full-size cars are the heaviest passenger cars, they
get slightly better gas mileage than trucks and SUVs.
A midsize car is shorter and lighter than a full-size
car, but it can still carry up to four adults comfort-
ably. It often has a smaller engine and gets better fuel
economy than full-size cars because of its reduced
curb weight and frontal cross-section.
A compact car usually has front-wheel drive with
a 4- or 6-cylinder engine. A compact car gets better
gas mileage because of its lower weight and small
height and width cross-section for reduced aerody-
namic drag. Less weight and less drag from passing
through air requires less energy for acceleration and
steady speed propulsion.
The minicompact car is the smallest car allowed on
public roads. It often only seats two people. Its wheel-
base is very short, and the diameter of its wheels and
tires is normally smaller than that of other conventional
vehicles. Their low weight and tiny engine make the
minicompact car one of the most fuel-effi cient vehicles
on the market. See Figure 1-6.
Vehicle Aerodynamics
Aerodynamics is the study of the motion of air
as it interacts with a moving object. In automotive
30% of weight
on rear tires
Vehicle length
Vehicle
width
70% of weight
on front tires
Figure 1-5. Note how the vehicle dimensions and weight
distribution are given for a passenger vehicle.
(www.thenewsmarket.com)
Figure 1-6. This micro car is an example of a minicompact car.