A - (frontal) Area. A is the area within an outline traced around the vehicle's extremity. Used for calculating aerodynamic drag.
A-B-A - Preferred test method for evaluating modifications under controlled conditions. (A) baseline data. (B) A change is introduced and further data is gathered. (A) The change is immediately removed and additional data is taken again under identical conditions. Identical results in the two "A" stages supports the quality of the "B" data, differing data in the “A” stages usually indicates further research required.
Belly Pan – Aerodynamic device underneath front of vehicle. Often smooth or nearly so, belly pans can be OE or aftermarket. Makes the underside of vehicle flatter and more aerodynamic.
BSFC - Brake Specific Fuel Consumption. Measurement of how much fuel is required to produce a specific amount of power from a given engine. Every engine has peak spot where under specific load and RPM it uses the least amount of fuel per unit of power produced. Measurement of efficiency.
CAI - Cold Air Intake.
Cd - Coefficient of Drag. A dimensionless number describing the aerodynamic drag of a body.
CdA - Coefficient of Drag times frontal area. Total drag is the product of both the shape and size of an object.
CODFISH - Coast On Demand Forced Ignition Shutoff. Same as EOC.
D15Z1 - VTEC-E engine in a Honda Civic VX, equipped with Lean Burn mode.
DFCO - Deceleration Fuel Cut Off, a condition where fuel injection stops when the accelerator is released and engine speed is above a target determined by the computer. The engine continues turning via the transmission, driven by the vehicle's momentum. Once below the speed threshold, fuel injection resumes allowing the engine to continue to run. DFCO is not in every vehicle and works differently in different vehicles.
DWB - Driving Without Brakes. Driving method designed to act as if the car has no brakes, forcing the driver to increase efficiency.
DWL - Driving With Load. Driver picks a target MPG figure to maintain, and adjusts the accelerator pedal accordingly. Used with instantaneous FE gauges.
EBH – Engine Block Heater.
ECU - Engine Control Unit. Engine computer.
ECT - Engine Coolant Temperature.
ECM - Engine Control Module. Engine computer.
EFI - Electronic fuel injection.
EGR – Exhaust Gas Recirculation.
EOC - Engine Off Coasting. Often used with P&G, but always involves the engine being turned off and restarted, either with a bump start or with a key.
EOI - Engine Off Idling. Turning your engine off at a drive-up window, fast food line, waiting for a train, etc. Certain Hybrids such as the Prius do this automatically as they use batteries to power accessories.
EV - Electric Vehicle.
FAS – Forced Auto Shutdown - The driver turns the engine off at times similar to when a hybrid might shut off its gas engine - for example, during a glide (which makes it EOC) and when stopped at a red light.
FE - Fuel Economy or Efficiency.
FWD – Front Wheel Drive.
FWT – Fahrenheit Water Temperature. Coolant temperature.
Grill Block – Partially blocking the grill openings on the vehicle for increased aerodynamics.
GS – GasSavers.org.
HAI - Hot Air Intake.
HHO - Dihydrogen Oxide - water. Typically used to mean water injection.
HPV - Human Powered Vehicle. Often a bicycle.
HX - Honda Civic HX.
IAT - Intake Air Temperature.
ICE - Internal Combustion Engine.
kWh - kilowatt hours - unit of measure for electricity consumption. 1 kWh is 1000 watts used per hour.
LPK - Litres per 100 km.
LRR - Low Rolling Resistance (tires).
MAF – Mass Air Flow (sensor).
MAP – Manifold Absolute Pressure (sensor).
MPG - Miles Per Gallon.
MFI - Mechanical fuel injection.
O2 - Oxygen or Oxygen Sensor.
OBD - On Board Diagnostics. System of sensors & computer(s) in an automobile. Versions are OBD-0, OBD-1, OBD-2.
OE – Original Equipment. “Dealer” parts or stock parts from the original vehicle.
OEM - Original Equipment Manufacturer. Sometimes used interchangeably to mean OE.
OTOH - on the other hand
P&G - Pulse and Glide. Driving technique of accelerating to an upper target speed then coasting lower target speed, such as 65 MPH / 50 MPH. The fuel economy of a P&G pattern is often significantly more fuel efficient than cruising at the same constant speed. Average speed would be closer to about 58 MPH. Uses either in-gear or neutral coasting. If the engine is turned off, it would be EOC.
PCV – Positive Crankcase Ventilation.
PSI - tire pressure.
PVC – Polyvinyl Chloride (plastic).
RPM - Revolutions Per Minute (engine speed).
RR - Rolling Resistance.
RWD – Rear Wheel Drive.
SG - ScanGauge fuel economy gauge/trip computer for use in 1996 and newer North American market vehicles. SG1 & SGI denote the first version, SG2 & SGII denote the second version.
SuperMID - Super Multi Information Display. Fuel economy & trip computer from a great guy in Japan.
TPS - Throttle Position Sensor.
VG - Vortex Generator. Aerodynamic device usually seen on larger vehicles.
VSS - Vehicle Speed Sensor. Signal used by the vehicle computer for speed and distance functions.
VX - Honda Civic VX.
WAI - Warm Air Intake.
WLR - White Line Rider (or Riding). A person who rides on the right side of the road, on, near or just to the right of the white line, to signal traffic they are running slower to save fuel.
WOT - Wide Open Throttle.
YMMV - Your mileage may vary