Overhang (automotive)
Encyclopedia
Overhangs are the lengths of a car, at the front and rear, which extend beyond the wheelbase. They are normally described as front overhang and rear overhang. Practicality, style, and performance are affected by the size and weight of overhangs.
saloon/sedans, measuring rear overhang is helpful in predicting the size of the trunk
. For these same vehicles, large front overhangs can accommodate larger engines. The Porsche 911
, produced since 1964, has always contained its entire flat-6
engine within its rear overhang, with the center of mass of the engine outside of the wheelbase. Large overhangs also contribute to safety
due to increased bulk, as well as space for crumple zones that provide defense for passengers in frontal and rear collisions. In the case of the 911, the rear-mounted engine
allows for increased practicality in the form of a small rear row of seats that would be impossible with a mid-engined
sports car.
, for which many old American cars with heavy V8 engines
were infamous. Front-engined
Ferraris
, such as the Ferrari 612 Scaglietti
place their engines within the wheelbase, so as to avoid the problem of understeer. Reducing overhanging weight in sports cars
is usually a priority, with the notable exception of the 911. In contrast, the excellent handling of the Mini, with its wheels pushed far out at each corner, can be partly credited to its small overhang.
Rear overhang may present a problem in large vehicles such as buses. Long rear overhang would require the driver to pay attention to nearby vehicles when turning at 90 degrees. Since the rear overhang is outside the wheelbase, it may hit a vehicle in the adjacent lane, especially when turning 90 degrees right (in a right-hand drive country).
Advantages
Large overhangs contribute to large vehicle dimensions, and the associated advantages of size. On front-enginedFront-engine design
A front-mounted engine describes the placement of an automobile engine in front of the vehicle passenger compartment.Historically, this designation was used regardless of whether or not the entire engine was behind the front axle line...
saloon/sedans, measuring rear overhang is helpful in predicting the size of the trunk
Trunk (automobile)
The trunk or boot of an automobile or car is the vehicle's main storage, luggage, or cargo compartment. Trunk is used in North American English and Jamaican English; boot is used elsewhere in the English speaking world. Trunk is also primarily used in many non-English speaking regions, such as...
. For these same vehicles, large front overhangs can accommodate larger engines. The Porsche 911
Porsche 911
The Porsche 911 is a luxury 2-door sports coupe made by Porsche AG of Stuttgart, Germany. It has a distinctive design, rear-engined and with independent rear suspension, an evolution of the swing axle on the Porsche 356. The engine was also air-cooled until the introduction of the Type 996 in 1998...
, produced since 1964, has always contained its entire flat-6
Flat-6
A flat-6 or horizontally opposed-6 is a flat engine with six cylinders arranged horizontally in two banks of three cylinders on each side of a central crankcase...
engine within its rear overhang, with the center of mass of the engine outside of the wheelbase. Large overhangs also contribute to safety
Automobile safety
Automobile safety is the study and practice of vehicle design, construction, and equipment to minimize the occurrence and consequences of automobile accidents. Automobile safety is the study and practice of vehicle design, construction, and equipment to minimize the occurrence and consequences of...
due to increased bulk, as well as space for crumple zones that provide defense for passengers in frontal and rear collisions. In the case of the 911, the rear-mounted engine
Rear-engine design
In automobile design, a rear-engine design layout places the engine at the rear of the vehicle. The center of gravity of the engine itself is past the rear axle...
allows for increased practicality in the form of a small rear row of seats that would be impossible with a mid-engined
Mid-engine design
A mid-engine layout describes the placement of an automobile engine between the rear and front axles. Another term for this is mid-ship.-Benefits:The mid-engine layout is typically chosen for its relatively favorable weight distribution...
sports car.
Disadvantages
Excessive weight that is concentrated outside of the wheelbase can interfere with accurate negotiation of corners at high speed. The rear-engined Porsche 911, with its engine far in the rear, was notorious for dangerous oversteer in its early days, and cars with engines far in the front often suffered from the opposite problem of understeerUndersteer
Understeer and oversteer are vehicle dynamics terms used to describe the sensitivity of a vehicle to steering. Simply put, oversteer is what occurs when a car turns by more than the amount commanded by the driver...
, for which many old American cars with heavy V8 engines
V8 engine
A V8 engine is a V engine with eight cylinders mounted on the crankcase in two banks of four cylinders, in most cases set at a right angle to each other but sometimes at a narrower angle, with all eight pistons driving a common crankshaft....
were infamous. Front-engined
Front-engine design
A front-mounted engine describes the placement of an automobile engine in front of the vehicle passenger compartment.Historically, this designation was used regardless of whether or not the entire engine was behind the front axle line...
Ferraris
Ferrari
Ferrari S.p.A. is an Italian sports car manufacturer based in Maranello, Italy. Founded by Enzo Ferrari in 1929, as Scuderia Ferrari, the company sponsored drivers and manufactured race cars before moving into production of street-legal vehicles as Ferrari S.p.A. in 1947...
, such as the Ferrari 612 Scaglietti
Ferrari 612 Scaglietti
The Ferrari 612 Scaglietti is a grand tourer produced by Ferrari between 2004 and 2010. It is a large two door fastback coupé. The 612 Scaglietti was designed to replace the smaller 456 M; its larger size makes it a true 4 seater with adequate space in the rear seats for adults.The design,...
place their engines within the wheelbase, so as to avoid the problem of understeer. Reducing overhanging weight in sports cars
Sports car
A sports car is a small, usually two seat, two door automobile designed for high speed driving and maneuverability....
is usually a priority, with the notable exception of the 911. In contrast, the excellent handling of the Mini, with its wheels pushed far out at each corner, can be partly credited to its small overhang.
Rear overhang may present a problem in large vehicles such as buses. Long rear overhang would require the driver to pay attention to nearby vehicles when turning at 90 degrees. Since the rear overhang is outside the wheelbase, it may hit a vehicle in the adjacent lane, especially when turning 90 degrees right (in a right-hand drive country).