Cruise control

Cruise control is a system that automatically controls the rate of motion of a motor vehicle. The driver sets the speed and the system will take over the throttle of the car to maintain the same speed.

Advantages and Disadvantages
Cruise control has many advantages but also some serious vices. Some of those advantages include:

• Its usefulness for long drives across sparsely populated roads. This usually results in better fuel efficiency.
• Some drivers use it to avoid unconsciously violating speed limits. A driver who otherwise tends to unconsciously increase speed over the course of a highway journey may avoid a speeding ticket. Such drivers should note, however, that a cruise control may go over its setting on a downhill which is steep enough to accelerate with an idling engine.

However, cruise control can also lead to accidents due to several factors, such as:

• The lack of need to maintain constant pedal pressure, which can help lead to accidents caused by highway hypnosis or incapacitated drivers; future systems may include a dead man's switch to avoid this.
• When used during inclement weather or while driving on wet or snow- and/or ice-covered roads, the vehicle not equipped with Electronic Stability Control could go into a skid. Stepping on the brake such as to disengage the cruise control often results in the driver losing control of the vehicle.

Driving over "rolling" terrain, with gentle up and down portions, can usually be done more economically by a skilled driver viewing the approaching terrain, by maintaining a relatively constant throttle position and allowing the vehicle to accelerate on the downgrades and decelerate on upgrades, while reducing power when cresting a rise and adding a bit before an upgrade is reached. Cruise control will tend to over throttle on the upgrades and retard on the downgrades, wasting the energy storage capabilities available from the inertia of the vehicle. The inefficiencies from cruise control can be even greater relative to skilled driving in hybrid vehicles. Many countries establish that it is illegal to drive within city limits with the cruise control feature activated.