Vehicular metrics

See also: Motorcycle testing and measurement

There are a broad range of metrics that denote the relative capabilities of various vehicles. Most of them apply to all vehicles while others are type-specific.

Measurement	American unit	Metric unit	Affects	General preference	Notes
0 to 60 mph	seconds	seconds	acceleration	lower is better
0 to 100 to 0 mph	seconds	seconds	acceleration & braking	lower is better	formerly common in British publications
Braking distance	feet	meters	safety	shorter is better
Brake specific fuel consumption	lb/(hp·h)	g/(kW·h)	economics, range	lower is better
Drag coefficient	(ratio)	(ratio)	economics, top speed, range	lower is better
Frontal cross-section area	sq ft	m2	economics, top speed, range	lower is better	if area is too small, vehicle becomes difficult to use
Fuel economy	mpg	l/100 km and km/L	economics, range	greater is better (mpg and km/L), lower is better (L/100 km)	must be specified on new vehicles for sale in the US & UK
Maximum g-force(s)	g or ft/s2	g or m/s2	acceleration	higher is usually better	measures cornering, braking or forward acceleration
Ground pressure	psi	pascals	traction	lower is better in soft ground, reduces bogging; higher with loose surface	has greater impact on off-road vehicles
Lift to drag ratio	-	-	economics, range	higher is better for aircraft	improved by narrow, long wings
Power	hp	kW	acceleration	higher is better	Refers to maximum power (high torque and speed)
Power-to-weight ratio	hp/lb	W/kg	acceleration	higher is better
Second moment	psi (lb·sq ft)	kg·m2	handling	lower permits quicker turn-in for cars, higher is more stable in straight line.	The moment of inertia about a vertical axis of a vehicle
Propulsive efficiency	%	%	economics, range	higher is better	For rockets and aircraft, percent of the energy contained in a vehicle's propellant converted into useful energy,
Roll center	inches	mm	handling	Too many variables to state a general preference.
Rolling friction	-	-	economics	lower is better	improved by narrow, high pressure tires
Shift time	mSec	ms	acceleration	lower is better	for vehicles equipped with automatic transmissions
Specific fuel consumption (thrust)	lb/(lbf·h)	kg/(kgf·h) or g/(kN·s)	economics, range	lower is better (for any given speed)	in airbreathing jet engines it is improved by using more inert air for propulsion (i.e. lower exhaust velocity), in rockets, higher exhaust velocity
Specific fuel consumption (shaft engine)	lb/(hp·h)	kg/(kW·h)	economics, range	lower is better	for shaft engines less fuel use for a given output power means higher efficiency
specific impulse	seconds	seconds or kN·s/kg	economics, delta-v/range	higher is typically better	in airbreathing jet engines it is improved by using more inert air for propulsion (i.e. lower exhaust velocity), in rockets, higher exhaust velocity
Top speed	mph	km/h	Maximum rate of straight line travel	higher is better	Electronically limited in some cars for safety (mostly due to concerns of tire failure at high speed)
Turning radius	feet	meters	handling	lower is better
Weight	lb	kg	acceleration, braking distance, traction, fuel consumption, tyre wear	lower is better for vehicle performance and taxation; larger is usually better for vehicles carrying loads
Weight distribution	%	%	handling, acceleration, traction	close to 50:50 (%Front:%Rear) is commonly considered better
Gross axle weight rating	lb/axle	kg/axle	durability, economics	larger is better for vehicles carrying loads	Ultimately limited by the hardness of the road surface and legal limits intended to limit damage to it