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Idle speed
The RPM of the engine free from load (all accessories off), at normal operating temperature and in neutral (or, in the case of an automatic transmission, park or neutral).
Idler pulley
A guide or tightening pulley for a belt or chain.
Ignition timing
The process of setting the time that a spark will occur in the combustion chamber (during the power stroke) relative to piston position and crankshaft angular velocity.
ILEV
Inherently low-emission vehicle. An emissions standard for alternative-fuel vehicles with closed and pressurized fuel systems.
Inboard brakes
A braking system that is located within the chassis of a vehicle instead of at its hubs.
In-car cellular phone
A cellular phone that either (i) has a handset built into the vehicle, or (ii) is a portable unit with an accompanying dock built into the vehicle that enables operation through the vehicle's entertainment and stereo system.
Incentive
Any kind of financial assistance from a vehicle manufacturer that, by reducing either the net price or the cost of financing/leasing, motivates customers to buy/lease a new vehicle. The most common incentives are customer cash rebates, low-interest financing and leases that are subsidized by the manufacturer.
Incentives and rebates
An auto industry term that encompasses all methods by which manufacturers attempt to stimulate vehicle sales and leases by reducing the net cost to consumers without reducing the vehicles' MSRPs, which includes customer rebates, dealer cash incentives and special leases.
 
 
Individual monitors
More than one video monitor in the rear passenger area of a vehicle with a rear seat entertainment system.
Instrumentation
Digital and/or analog displays used to convey to the driver information such as dynamic engine parameters, operating conditions, RPM, speed and water temperature.
Instrumented testing
The analysis of a vehicle's performance characteristics using precise scientific equipment.
Insurance Institute for Highway Safety
Sometimes referred to as the "IIHS." An organization created by the insurance industry for the purpose of reducing the losses (deaths, injuries and property damage) from vehicle crashes.
Integrated turn signal
A turn signal light that is mounted on or in a vehicle's sideview mirror.
Intelligent alternator
An alternator that operates primarily when the engine has no need for power, i.e., when coasting or during braking. The alternator remains passive while the vehicle is under power, with needed electrical power provided by the battery, for the purpose of improving the vehicle's fuel efficiency.
Intelligent car
A vehicle that employs the latest in telemetrics, driver awareness and/or pedestrian safety technology.
Interior lighting
Halogen lamps or light-emitting diodes (LEDs) used to illuminate a vehicle's interior space.
Interior trim
Wood, composite, leather or metal adornments intended to supplement the aesthetic elements of a vehicle's interior.
Invoice
Also referred to as "Invoice Price." The price that appears on the invoice that the manufacturer sends to the dealer when the dealer receives a vehicle from the factory.