CDL · General Knowledge · United Kingdom

General Knowledge for the CDL Exam — UK candidates

20% of the CDL test plan. The General Knowledge test (50 multiple-choice questions) is required for every CDL class and covers vehicle systems, road rules, and emergency procedures. Calibrated for British candidates.

Examiners do not award marks for content alone — they award them for the ability to demonstrate competency in the precise format the test demands. General Knowledge sits at roughly 20% of the Commercial Driver License content distribution — Every CDL applicant takes General Knowledge. Topics include vehicle inspection, basic control, shifting, communicating with other drivers, accident procedures, and driver wellness. In 2024, the published first attempt rate for CDL candidates globally was 65% (FMCSA — applies to UK candidates testing in the U.S.). For UK candidates preparing for CDL, the calibration of study to local context matters: UK candidates often take exams for both domestic licensure (NMC, GMC) and migration purposes. IELTS UKVI is a separate, higher-stakes track.

Common failure modes

These are the patterns that cause most candidates to lose marks on this topic. Recognising them in advance is half the work.

!Misidentifying the controlled-braking vs stab-braking technique
!Confusing the proper following distance rule (1 second per 10 ft of vehicle length, plus 1 second above 40 mph)
!Wrong answer on hazardous-conditions reduced-speed rules
!Confusing the disqualification offences (DUI, reckless, leaving the scene)

Study tips

1Drill following-distance math: 50 ft trailer at 35 mph = 5 seconds; at 50 mph = 6 seconds.
2Memorize disqualification offences and their durations — first DUI = 1 year, second = lifetime.
3Practice stab-braking vs controlled braking with the FMCSA definition.
4Know the wellness requirement: 8 hours sleep, no driving over 11 hours after 10 off.
5In the UK, CDL schedules and reschedules align with state holiday calendars and post-Brexit fee adjustments — confirm pricing on the awarding body's site before booking.

Sample CDL General Knowledge questions

These sample items mirror the format and difficulty of real CDL questions. Practice with thousands more on the free Koydo question bank.

1
You should keep how many seconds of following distance for every 10 feet of vehicle length at speeds below 40 mph?
- A1 secondCorrect
- B2 seconds
- C3 seconds
- D5 seconds
Why this answer?
The CDL rule is 1 second per 10 feet of vehicle length below 40 mph. Above 40 mph, add 1 second. A 60-foot rig at 55 mph thus needs 7 seconds of following distance.

Frequently asked questions

How many questions are on the General Knowledge test?

Most states use a 50-question multiple-choice format. You must answer at least 40 (80%) correctly to pass.

What is the CDL General Knowledge pass rate for British candidates?

The published first attempt rate for CDL candidates globally in 2024 was 65%, according to FMCSA — applies to UK candidates testing in the U.S.. Pass rates within specific topics like General Knowledge are not separately published, but the topic represents roughly 20% of the exam.

How long should British candidates study General Knowledge for the CDL?

For most candidates, focused mastery of General Knowledge requires 20–40 hours of deliberate practice — drilling sample questions, reviewing failure modes, and timing yourself against exam conditions. UK candidates often take exams for both domestic licensure (NMC, GMC) and migration purposes. IELTS UKVI is a separate, higher-stakes track. Combine General Knowledge study with full-length mock exams in the final two weeks before your test date.

Practice CDL questions free with Koydo.

Air-brakes, hazmat, pre-trip — every endorsement, every state. Built with a Pass Guarantee.

Start free CDL practice →Practice this topic with AI