Measuring driving behaviour enables you to raise awareness, coach and reward your drivers — improving both safety and efficiency across fuel costs, CO2 emissions, maintenance and insurance.
With Frotcom, drivers receive a straightforward score between 1 and 10 according to their overall driving behaviour. An analysis report is also generated, providing personalised guidance on how they can improve.
At some point, however, you may need to go deeper than the score to help train individual drivers. This guide explains exactly what the numbers mean — so your coaching conversations are grounded in fact, not guesswork.
For additional insights into driving behaviour, you may also wish to use AI dashcams, which combine video evidence with telematics data for even more effective coaching.
What the Numbers Mean
Frotcom measures driving behaviour events in metres per second squared (m/s²) — the same unit used to measure acceleration, braking and cornering forces. A quick rule of thumb: 1 m/s² ≈ 2.2 mph gained or lost every second, and 10 m/s² is roughly the force of gravity.
Events are rated across three bands — Firm, Hard and Extreme — for each of the three key measures.
Acceleration
Hard above 4 m/s², extreme above 5 m/s². Most ordinary cars and vans cannot exceed 3–4 m/s² even flat out, so high figures say a lot about how the driver is using the accelerator.
Gaining around 9 mph every second. The driver has pressed the accelerator most or all of the way down. Passengers are pushed firmly back into their seats; loose items slide backwards.
Likely causes: Pulling away hard from lights or junctions, rushing to join fast traffic, or overtaking.
Suggested coaching wording
"Hard acceleration — you were gaining speed at around 9 mph every second, far more than normal driving needs. Smooth, gradual acceleration saves fuel, reduces wear and gives you more time to react."
Gaining around 11 mph every second — sports car pace. Most ordinary petrol or diesel vehicles cannot reach this, except perhaps a brief spike as the clutch bites. Powerful cars and electric vehicles can, with little effort. Tyres may chirp or spin, especially in the wet.
Likely causes: Deliberately aggressive starts, wheelspin, or — in an electric vehicle — simply flooring it out of habit.
Suggested coaching wording
"Extreme acceleration, at the level of a sports car launch. At this force, the tyres are near their grip limit, especially on wet or uneven roads, leaving little control margin if something unexpected happens."
Things to check
- Vehicle type: 5 m/s² is unremarkable in a performance electric car but nearly impossible in a small van. A reading this high from a low-powered vehicle may point to a sensor issue.
- Duration: Potholes, speed bumps and kerbs can cause very short spikes. A genuine hard acceleration lasts a second or more and comes with rising speed.
Braking
Hard above 4 m/s², emergency stop above 6 m/s². Every car's brakes can stop it far harder than its engine can accelerate it, so braking has more headroom than acceleration. A useful reference: the Highway Code stopping distances assume braking at around 6.5 m/s² — a full emergency stop on a dry road.
Losing about 9 mph every second. Much harder than a normal stop — from 30 mph, the car stops in roughly 3.5 seconds and 22 metres of braking. Passengers lurch forward into their seatbelts; bags slide off seats.
Likely causes: Late braking for lights, junctions or queues; following too closely; distraction causing a late reaction.
Suggested coaching wording
"Hard braking — you were slowing at around 9 mph every second, well beyond a normal stop. This usually means a hazard was spotted late. Looking further ahead and leaving a bigger gap lets you brake earlier and more gently."
An emergency stop, close to what the Highway Code assumes for its stopping distances. ABS may activate. Seatbelts lock, everything loose flies forward, and tyres may squeal.
Likely causes: A genuine emergency — a pedestrian stepping out, a car pulling across — or a near-miss caused by tailgating.
Suggested coaching wording
"Emergency braking — braking this hard means something needed an immediate stop. If this happens regularly, it's a sign you're leaving too little time to react."
Important note on context
A single harsh brake can be good driving — avoiding a collision. It's the pattern that matters, not one event. Repeated harsh braking points to tailgating or poor anticipation; a rare emergency stop may be the right call. Avoid penalising a driver for one emergency stop.
Cornering
Hard above 4 m/s², extreme above 5 m/s² — and it is the riskiest of the three. The grip limit is lower than many drivers realise and drops sharply in the wet: most cars lose grip at around 7–9 m/s² on dry roads, but only 4–6 m/s² on wet ones.
A sideways push of about 40% of body weight. Taking a bend or roundabout well faster than normal. On a wet road, this is already close to the edge of grip. Passengers lean hard against doors and reach for grab handles.
Likely causes: Entering bends or roundabouts too fast, turning sharply at junctions, or swerving.
Suggested coaching wording
"Harsh cornering — you took this turn fast enough to throw passengers sideways. In wet conditions, this is close to the point where tyres can lose grip. Slowing down before the bend, not in it, keeps the car stable."
A sideways push of about half body weight — sports-driving territory. On a wet road, the car is at or beyond the grip limit. On a dry road, there is little margin left for a surprise such as gravel, a pothole or a diesel spill.
Likely causes: Excessive speed into a bend, or a sudden swerve to avoid something.
Suggested coaching wording
"Extreme cornering — the car was close to the limit of tyre grip. A small change in road surface could have caused a skid. Brake before the bend and take it at a speed where you could stop if something were around the corner."
Things to check
- Road features: Camber, kerbs and potholes can create short spikes worth investigating before raising with the driver.
- Weather: If conditions were wet, consider that lower cornering thresholds are acceptable — 4 m/s² in the wet is far more dangerous than 4 m/s² on a dry road.
Summary of Thresholds
| Event | Firm | Hard | Extreme |
|---|---|---|---|
| Acceleration | 3–4 m/s² | 4–5 m/s² | 5+ m/s² |
| Braking | 3–4 m/s² | 4–6 m/s² | 6+ m/s² (emergency stop) |
| Cornering | 3–4 m/s² | 4–5 m/s² | 5+ m/s² (lower in wet) |
Rule of thumb: 1 m/s² ≈ 2.2 mph gained or lost per second. 10 m/s² is approximately the force of gravity.
Using the Data to Coach Effectively
The Frotcom driving behaviour score gives you an at-a-glance view of each driver's performance. The event data behind it gives you something more valuable: the ability to have a specific, evidence-based conversation.
When reviewing events with a driver, focus on patterns, not one-offs. A single harsh brake may have been exactly the right response. Repeated harsh braking in the same area of a route, however, points to a habit worth addressing.
Use the suggested coaching wording in each section above as a starting point — adapt the tone to the individual. The goal is awareness and improvement, not blame.
Want to know how Frotcom's driving behaviour scoring and dashcam integration can support your driver coaching programme?
Talk to Frotcom UK →