Auto Information (AI)
Auto Information (AI) tests automobile technology — how engines and car systems work. On the computer ASVAB it's its own subtest; on the paper test it's combined with Shop Information into one Auto & Shop score.
Practise Auto Information freeAlready know what's on it and still stuck? How to improve your Auto Information score.
The engine
Learn the four-stroke cycle in order — intake, compression, power, exhaust. Gasoline engines use a spark plug to ignite the air–fuel mixture; diesel engines ignite by compression and have no spark plug. Know the basic parts (cylinders, pistons, valves).
The major systems
Ignition and fuel (spark plugs, injectors); cooling (radiator, thermostat, water pump); lubrication (oil, oil pump); exhaust and emissions (muffler, catalytic converter); charging and electrical (battery, alternator, starter); the drivetrain (clutch, transmission, differential); and brakes and suspension/steering.
Parts and symptoms
Know what each key part does and the symptom when it fails — a dead battery vs. a failing alternator, an overheating engine (cooling), a slipping clutch. Questions often describe a symptom and ask for the cause or the part.
Test-day strategy
If you've worked on cars, much of this is familiar. Focus on the four-stroke cycle, the job of each system, and gas vs. diesel — these come up most.
Key takeaways
- The four-stroke cycle (intake, compression, power, exhaust) is the single most tested idea.
- Gasoline = spark ignition; diesel = compression ignition.
- Know each system's job: charging, cooling, drivetrain, brakes.
Start a free Auto Information practice set — timed, with a worked explanation after every question.
Go to Auto Information practiceFree sample Auto Information questions
A few sample questions with worked answers. Our free Auto Information practice set has 151 questions in total — every one with a full explanation.
- A.the alternator
- B.hydraulic pressure ✓
- C.engine vacuum
- D.a return spring
- A.Intake
- B.Exhaust
- C.Compression
- D.Power ✓
- A.Power
- B.Exhaust ✓
- C.Intake
- D.Compression
- A.Match engine speed to demand ✓
- B.Cool the front brakes
- C.Charge the main battery
- D.Ignite the engine's fuel
- A.cylinder head and the block ✓
- B.two battery terminals
- C.front wheel and the axle
- D.fuel tank and the pump
Auto Information cheat sheet
The formulas and facts worth memorising for this subtest. See all ASVAB cheat sheets →
- Four-stroke cycle in order: Intake → Compression → Power → Exhaust
- Gasoline engine ignites with a SPARK PLUG; diesel ignites by COMPRESSION (no spark plug)
- Cooling: radiator, thermostat, water pump, coolant/antifreeze
- Charging: battery, ALTERNATOR (charges the battery), starter
- Drivetrain: clutch, transmission (changes gear ratios), differential
- Emissions: catalytic converter · Lubrication: oil & oil pump
- Shock absorbers connect the axle to the chassis