Vehicle Safety Glossary

Definitions of terms used throughout this site. All definitions are based on official NHTSA documentation and federal motor vehicle safety regulations.

NHTSA

National Highway Traffic Safety Administration. The federal agency within the U.S. Department of Transportation responsible for vehicle safety. NHTSA sets and enforces safety performance standards, investigates defects, and manages vehicle recall campaigns.

Recall

A recall occurs when a manufacturer or NHTSA determines that a vehicle, equipment, car seat, or tire creates an unreasonable safety risk or fails to meet minimum safety standards. The manufacturer must notify owners and provide a free remedy (repair, replacement, or refund). Recalls are identified by a NHTSA Campaign Number (e.g., 23V858000).

Complaint (ODI Complaint)

An owner-reported vehicle safety problem submitted to NHTSA's Office of Defects Investigation (ODI). Complaints are unverified consumer reports - they have not been independently confirmed by NHTSA or the manufacturer. Each complaint is assigned an ODI Number.

NCAP

New Car Assessment Program. NHTSA's crash testing program that evaluates vehicle safety by conducting frontal crash, side crash, and rollover resistance tests. Results are published as 1-to-5-star safety ratings.

VIN

Vehicle Identification Number. A unique 17-character code assigned to every motor vehicle when it is manufactured. The VIN identifies the vehicle's make, model, year, engine, transmission, and manufacturing plant. It is printed on the dashboard (visible through the windshield) and on the driver's door jamb sticker.

Campaign Number

A unique identifier assigned by NHTSA to each recall campaign. The format is typically YYVNNN000 where YY is the year, V indicates a vehicle recall, and NNN is the sequential number. Example: 23V858000 is the 858th vehicle recall opened in 2023.

Safety Rating (Stars)

NHTSA's 1-to-5-star rating based on crash test results. Five stars indicates the lowest risk of serious injury in that test type. Ratings are given separately for frontal crash, side crash, and rollover resistance. Stars can only be compared between vehicles of similar weight class.

Frontal Crash Rating

NHTSA crash test where the vehicle is driven into a fixed barrier at 35 mph. Sensors on driver and front passenger dummies measure the probability of serious injury. Separate ratings are given for the driver side and passenger side.

Side Crash Rating

NHTSA conducts two side-impact tests: a side barrier test (3,015-pound moving barrier strikes the driver's side at 38.5 mph) and a side pole test (vehicle slides sideways into a rigid pole at 20 mph). Separate ratings are given for the driver and rear passenger.

Rollover Resistance Rating

A rating based on the vehicle's Static Stability Factor (track width divided by twice the center of gravity height) combined with a dynamic driving maneuver test. The result is expressed as both a star rating and a rollover probability percentage.

TSB (Technical Service Bulletin)

A document issued by a vehicle manufacturer to its dealers describing a known problem and its recommended repair procedure. TSBs are not recalls - they address issues that may not be safety-related or that affect only some vehicles. TSBs are sometimes issued before or instead of a recall.

ODI

Office of Defects Investigation. The division within NHTSA that receives and analyzes consumer complaints, conducts defect investigations, and manages recall campaigns.

Preliminary Evaluation (PE)

The first formal stage of an NHTSA defect investigation. A PE is opened when complaint data suggests a possible safety defect pattern. NHTSA collects additional information from the manufacturer and vehicle owners.

Engineering Analysis (EA)

The second stage of an NHTSA investigation, following a Preliminary Evaluation. An EA involves detailed technical analysis, vehicle inspections, and testing. An EA can result in a mandatory recall order if NHTSA confirms a safety defect.

ESC (Electronic Stability Control)

A computerized system that detects and reduces loss of traction by automatically applying brakes to individual wheels. ESC has been required on all new passenger vehicles sold in the United States since model year 2012 (per FMVSS 126).

FMVSS

Federal Motor Vehicle Safety Standards. Regulations issued by NHTSA that set minimum safety performance requirements for motor vehicles and equipment. Examples: FMVSS 208 (occupant crash protection), FMVSS 126 (electronic stability control).

Defect

As defined by federal law (49 U.S.C. § 30102), a defect includes any defect in performance, construction, a component, or material of a motor vehicle or motor vehicle equipment. A safety-related defect is one that creates an unreasonable risk of accidents or injury.