Grey fleet management scaling checklist: What breaks as you grow from 10 to 50+ drivers

If you’re responsible for approving mileage claims — whether you’re an office admin, HR manager, finance lead, operations manager, or team manager — this will probably sound familiar:

An employee needs to visit a client. They take their own car, submit a mileage claim, and it gets paid. Job done. No issues, no red flags. It feels simple, even harmless.

Until the business grows.

What worked fine for a few people starts to wobble at ten drivers, gets messy at 15 or 25, and before you know it, turns into a lot of admin — and potential legal or financial risk — once you hit 50, if nothing changes.

Most grey fleets don’t start with a policy decision. They start with convenience. The problem isn’t employees using their own cars, it’s what happens as numbers grow. 

Processes that were easy to manage at a small scale quickly break down, making mileage tracking, documentation, and compliance harder for you to stay on top of.

Our research with teams managing employee mileage shows a clear pattern:

“As teams grow, informal mileage processes break down — not due to bad intent, but because checks and oversight don’t scale.”

Source: Sales & Onboarding Call Analysis, 2025

So how do you stay in control as your organisation grows?

We’ll break down what typically starts to fail as a grey fleet scales — and what you need to put in place, step by step, to keep it manageable.

Before you scale: Is grey fleet the right model for your business?

Grey fleet, aka employees driving their own vehicles for work, can make sense whether your organisation is small, growing, or well established. 

And to confirm a grey fleet is (still) the right decision for your business, you can assess two key factors.

1. Look at business mileage

As a rule of thumb, most industry sources suggest that grey fleet works best when annual business mileage per vehicle stays below 10,000. 

Above this level, the cost balance often shifts – particularly because HMRC mileage rates drop after 10,000 miles, which changes the economics of reimbursement.

At around 8,000 business miles per year, it’s worth reviewing whether a company car or maybe a lease would be more cost-effective.

Also read: Company car vs. grey fleet - what’s right for you 

2. Look at roles across your organisation

Using a personal car for work trips is typically well-suited to office- or home-based employees who drive occasionally, as well as role-based workers such as care workers, consultants, or community staff. 

These roles may involve regular travel, but don’t require a branded vehicle, specialist equipment, or tight central control.

When does a company or commercial fleet make more sense?

Company cars or commercial vehicles tend to be a better fit when the vehicle itself is central to the role, for example, where annual mileage is consistently high, specialist tools or equipment are required, or the business needs tighter control over vehicles, branding, or availability.

Whether you opt for grey fleet management or a company car fleet, what matters most is choosing the right setup and making sure the people managing it are properly supported with the right tools and processes.

Also read: Car allowance vs company car

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What happens when your grey fleet grows?

A grey fleet doesn’t break as you grow — manual processes do. What works for a handful of drivers quickly becomes harder to manage as numbers increase, unless your processes scale with them.

Drawing on Driversnote’s experience with automatic mileage tracking for companies and individuals, we’ll walk through what typically changes at 10, 25, and 50 drivers. At each stage, we’ll focus on:

• Processes: how mileage tracking and admin are handled
• Compliance: including mileage records and legal checks
• Ownership: who’s responsible for what
• Early signals: signs you’re ready for the next stage

So you’ll know exactly what to put in place — and what to do next — to stay in control as you grow.

10 drivers: Replace the manual processes

Processes: How mileage tracking and admin are handled

In our experience, organisations with fewer than ten drivers often handle mileage administration (tracking, reporting, approving, and documenting) manually and inconsistently.

Individual drivers may use their own mileage tracking apps, but the business as a whole hasn’t yet committed to a structured or automated approach.

Managers receive mileage claims in mixed formats — spreadsheets, PDFs, or even emails — and approve a small number of claims one by one each month.

Compliance: Including mileage records and legal checks

Compliance at this stage is often handled on trust:

• Driving licences checked at onboarding
• Insurance reviewed once a year
• MOTs assumed to be valid
• Mileage reports saved in a shared folder

With a small group, this can feel reasonable. 

But it often leaves a lingering doubt: are you actually meeting your legal obligations and HMRC requirements? And if an audit does happen, will the right documentation be easy to access, or will it mean hours of manual checks and backtracking?

In the UK, this becomes relevant sooner than many expect. Once you have five or more employees, you’re legally required to have a written health and safety policy, and that policy must include how work-related driving is managed.

Ownership: Who’s responsible for what?

When an organisation has fewer than ten drivers, ownership of the grey fleet is typically informal. Responsibilities are implicit rather than clearly defined, and processes tend to live in people’s heads rather than being documented.

In practice, mileage is usually approved by the driver’s direct manager, who knows the driver and the trips, and then passed to finance or a bookkeeper for payment — often via payroll or an expense system.

Early signals: Signs you may be ready for the next stage

As you approach ten drivers, manual and undocumented mileage processes often start to feel harder to manage and less consistent.

At this point, some organisations choose to introduce a mileage tracking app as a low-effort way to reduce admin, bring consistency to reporting, and support HMRC compliance – without adding unnecessary complexity.

The signals below can help you sense-check whether your current mileage process is still working for your organisation:

• Mileage reports start arriving in different formats
• Approvals take longer than you’d expect
• Trip logging begins to feel repetitive or time-consuming for drivers
• Vehicle and document checks rely on memory rather than reminders

If any of these sound familiar, it may be time to think about scaling your mileage process.

What teams often scale at this stage

• A single, consistent way for drivers to submit mileage
• Clear ownership of licence, insurance, and MOT checks
• Earlier visibility into trip volume per driver

Is your organisation compliant? Download our risk assessment template

25 drivers: Admin is a bottleneck

Processes: How mileage tracking and admin are handled

By the time a grey fleet reaches 25 drivers, mileage administration needs to be automated, from tracking to approval.

This is echoed in our research with what drives new team administrators towards a solution like Driversnote:

“Reviewing mileage reports is consistently described by administrators as the most time-consuming part of the process, largely due to manual verification and missing or inconsistent data.”

Source: Sales & Onboarding Call Analysis, 2025

This stage is also where costs can start to drift. Small inaccuracies, like rounded distances, missed or duplicate trips add up across dozens of drivers. No one is acting in bad faith, but mileage inflation becomes almost inevitable without properly recorded trips.

As one operations manager we spoke to during our research explained:

“When you look at the expenses, people are just putting ‘I drove 200 miles’. But nobody really drives exactly 200 miles — it might be 198 or 203. At that point, you realise people are just estimating.”

- Operations &  finance stakeholder
Source: Sales & Onboarding Call Analysis, 2025

Compliance: Including mileage records and legal checks

Compliance checks follow the same pattern. Licences, insurance, and MOTs are still checked — just not always at the right time or with the same consistency.

An insurance policy renewed without business use, or a document that quietly expires, is easy to miss when admin time is already stretched.

Ownership: Who’s responsible for what

This is where unclear ownership starts to hurt the grey fleet management. Managers are approving more claims than they can realistically review, finance is processing higher volumes, and no one has mapped the end-to-end grey fleet process.

Things still get done, but accountability becomes blurred.

Early signals: Signs you’ve outgrown manual processes

Admin time spent reviewing and approving mileage keeps increasing
Employees push back on manual or clunky mileage tracking
Different teams track and approve mileage in different ways

What to scale at this stage

Instead of adding more admin time, focus on scaling the system:

• Invest in a team solution with automatic mileage tracking and simple approval flows
• Standardise driver reporting so HMRC-compliance is built in and done right by default
• Put a recurring annual process in place to check licences, insurance, and MOTs
• Give managers visibility to approve mileage with confidence
• Write down the process — who approves, who checks, who pays, and when

Also read: Grey fleet policy guide & template

50+ drivers: Structure and compliance become crucial 

Processes: How mileage tracking and admin are handled

Once your organisation reaches around 50 drivers, the challenge shifts. It’s no longer just about saving time on mileage approvals, it’s about having structure, consistency, and confidence.

Grey fleet ownership without systems becomes impossible. Relying on managers knowing their teams, or finance keeping things roughly in order, isn’t sustainable.

When answers rely on spreadsheets, shared folders, or “we usually check this,” things start to feel harder than they need to be.

Compliance: Including mileage records and legal checks

At this scale, simple questions come up more often:

• Are drivers insured for business use?
• Are vehicles roadworthy?
• Are checks happening regularly, and can we show them if asked?

Without clear systems, gaps are inevitable.

Ownership: Who’s responsible for what

Grey fleet doesn’t need to sit in a single ‘perfect’ department. But responsibility must be explicit.

Whether ownership sits with operations, finance, HR, health & safety, or a combination, it needs to be clearly defined and supported by shared tools that ensure consistency across teams.

Early signals: Signs your setup is starting to creak

Mileage data and documents live in multiple places
Policies are clear, but enforcement varies by team
Licence, insurance, and MOT checks rely on reminders
Managers spend more time approving claims than they’d like

These are normal growing pains, and a sign it’s time to add structure.

What to scale at this stage

At this point, structure replaces goodwill:

• Centralised, audit-proof mileage records across all drivers
• Automatic mileage tracking to reduce errors and manual input
• Simple, consistent approval flows for managers
• Clear audit trails that are easy to access when needed
• Defined ownership of responsibilities, even when multiple teams are involved

For drivers, reporting stays easy. For managers, approvals are faster. And for the organisation, grey fleet becomes a well-managed part of day-to-day operations, not something that quietly grows more complex over time.

What keeps your grey fleet afloat 

The pattern is consistent:

• At 10 drivers, you can fly without explicit ownership;
• At 25, ownership, documentation and automation become critical;
• At 50+, ownership without reliable systems simply doesn’t work.

Organisations that manage their grey fleet well rely on systems.

• Automatic trip tracking replaces estimates
• Standardised reports replace ad-hoc formats
• Alerts replace memory
• Visibility replaces trust

This reduces disputes, protects drivers, and gives admins and managers confidence that the process will withstand scrutiny.

Get the grey fleet management scaling checklist

This checklist helps you identify:

• The warning signs at 10, 25, and 50+ drivers
• What to scale at each stage
• Where manual processes are putting pressure on admin, cost, and compliance

👉 Get your grey fleet management scaling checklist below

The real cost of “managing it later”

Many organisations delay improving grey fleet management because it feels cheaper to keep things manual. In reality, an unmanaged grey fleet accumulates hidden costs: admin time, overpayment, compliance exposure, and stress when something goes wrong.

Putting the right ownership, processes, and tools in place as you grow reduces admin effort, keeps costs predictable, and gives everyone confidence that your organisation's grey fleet is working as it should. The earlier you scale the system, the easier it is to manage — no matter how large your organisation becomes.