Most Irish businesses with travelling staff are running a grey fleet. Most don't have the systems to manage it properly. If you run a firm where staff use their own cars for work - site visits, client meetings, travel between offices - that's grey fleet, and the term is worth understanding even if you've never used it.
This guide explains what grey fleet means, why the term exists, and what it implies for your business from a compliance and operational perspective.
The short version
Grey fleet refers to employees' personal vehicles used for business purposes. When your engineer drives their own Passat to a site inspection and claims mileage, that's grey fleet. The company doesn't own or lease the car, but you're paying for its business use and you carry responsibilities around that payment.
The "grey" comes from the governance challenge. These vehicles sit in a grey area: you have limited visibility and control over them, but you remain responsible for correct mileage reimbursement, tax compliance, and duty of care.
Why the term exists
Fleet management evolved in industries with company-owned vehicles - utilities, telecoms, logistics. Those organisations needed software to track their vans and trucks, manage maintenance schedules, and control fuel costs.
The engineering consultancy with 40 staff driving their own cars to sites doesn't fit that picture. Neither does the accountancy practice with partners visiting clients in their personal BMWs. These vehicles aren't fleet in the traditional sense, but they create similar compliance obligations. The industry needed a term to distinguish employee-owned vehicles used for business from company-owned assets. Grey fleet filled the gap.
The four types of business vehicles
Understanding where grey fleet fits requires seeing the full picture.
Company fleet (white fleet). Vehicles the organisation owns outright. Common in utilities, delivery companies, and construction contractors where vehicles are essentially tools - vans fitted with equipment, trucks carrying materials. The employer handles everything: purchase, insurance, maintenance, fuel cards. Full visibility, full control, full cost.
Leased fleet. Vehicles the company leases and assigns to employees or pools. Operationally similar to company fleet, different on the balance sheet. Common for sales teams and service technicians in larger organisations. The leasing company handles the vehicle lifecycle; you manage allocation and usage.
Salary sacrifice and company car schemes. Employee takes a lower gross salary in exchange for a company-provided vehicle. Popular for electric vehicles in particular due to the tax treatment. The vehicle is technically employer-provided, but the employee chooses it and treats it as theirs. (The 2026 BIK threshold change reshaped the company-car-vs-grey-fleet decision for some employees - worth recalculating if you run a mix.)
Grey fleet. Employee-owned vehicles used for business. The employer reimburses mileage at approved rates (Civil Service rates in Ireland, HMRC rates in the UK). No vehicle ownership or lease obligation, but you're still responsible for getting the reimbursement right.
Why professional services firms run grey fleet
Engineering consultancies, surveying firms, quantity surveyors, accountants with distributed clients - these businesses almost universally run grey fleet. The reasons are practical.
Unpredictable usage patterns. A structural engineer might drive 200 km one week and 20 km the next. Company cars don't make sense when usage varies that much. You'd be paying for vehicles sitting idle in driveways.
Employee preference. Many people prefer driving their own car. They've chosen it, they know it, they don't want to be assigned whatever the company negotiated in a bulk lease deal.
Lower capital exposure. No fleet means no depreciation, no vehicle management overhead, no disposal hassles. You reimburse actual business use.
Recruitment flexibility. "Use your own car, we'll pay mileage" is simpler to offer than managing vehicles across 50 employees with different needs. It scales up and down without contractual complexity.
Geographic distribution. When staff work from home or across multiple offices, centralised fleet management becomes impractical. Grey fleet handles distributed teams naturally.
The trade-off is governance. Grey fleet is administratively messy: variable engine sizes, mileage band calculations, project allocation, and the perpetual question of whether claims are accurate.
The compliance reality
Three areas where grey fleet stops being theoretical and starts mattering.
Irish Revenue mileage bands
Ireland uses Civil Service mileage rates that vary by engine size and cumulative annual distance. The rates aren't flat - they decrease as an employee drives more. For 2024, a car over 1500cc reimburses at 64.78 cent per kilometre for the first 1,500 km, dropping to 30.11 cent per kilometre once they exceed 5,501 km.
This creates a calculation problem. When someone's cumulative mileage crosses a band threshold mid-trip, the reimbursement has to be split proportionally. If Eileen has driven 5,400 km this year and submits a 200 km trip, the first 100 km is at the higher rate, the next 100 km at the lower rate.
Most spreadsheet-based systems get this wrong. A single missing trip can distort every calculation that follows it, and generic expense apps ignore the band logic entirely.
Enhanced Reporting Requirements (ERR)
The Finance Act 2022 introduced Enhanced Reporting Requirements that increase scrutiny on expense reimbursements. Revenue now expects more detailed, structured data on what employees are claiming and why.
Organisations using informal processes - email approvals, end-of-month spreadsheet reconciliation, manual rate lookups - face compliance risk they may not have anticipated.
Duty of care
Beyond the numbers, employers have a duty of care for staff driving on business. Grey fleet limits direct control - you can't mandate maintenance schedules on vehicles you don't own - but you should be aware of who's travelling where and when. Some firms use the trip submission process as a lightweight lone-worker awareness system. If someone's driving to a remote site for a meeting, their manager knows about it.
Who has grey fleet, and who doesn't
The pattern is fairly predictable.
Heavy company or leased fleet:
- Utilities (engineers in vans all day)
- Telecoms (service technicians with equipment)
- Pharma and medical sales (high-mileage reps)
- Logistics and delivery (obviously)
- Construction contractors (vehicles as tools)
Mixed fleet:
- Large engineering consultancies
- National professional services firms
- Healthcare organisations with community staff
- Charities with field workers
Primarily grey fleet:
- Mid-sized engineering consultancies
- Quantity surveying firms
- Regional accountancy practices
- Solicitors with multiple office locations
- Smaller construction project management firms
- Environmental consultancies
- Public sector bodies with travelling officers
If your business sits in that last category, you're managing grey fleet whether you've formalised it or not.
What good grey fleet management looks like
The gap in the market isn't awareness. Most finance directors know mileage is a headache. The gap is tooling that fits the grey fleet reality without the overhead of enterprise fleet management.
Effective grey fleet management handles five things.
Rate calculations automatically. The system knows Irish Revenue bands and applies them correctly, including mid-trip band splits. No manual lookups, no Excel formulas that break when someone changes a cell.
Project allocation. For consultancies and professional services, every trip cost needs to attach to a job code or project number. This is essential for client billing and for understanding project profitability.
Approval workflows. Many firms need to pre-approve trips before travel - budget control, lone-worker awareness - rather than just logging claims after the fact.
Audit trails. When Revenue asks questions, when a client queries project costs, when internal finance needs to trace a payment, there's a clear record of who submitted what, who approved it, and how the calculation was done.
Clean payroll export. At month-end, finance shouldn't be spending hours reconciling spreadsheets. The data should be ready to export in the format your payroll system needs.
If you have grey fleet - and you almost certainly do if your staff use personal cars for work - the harder question is whether you have systems that handle it properly.
Where OdoHub fits
I built OdoHub for grey fleet compliance: submission workflows, correct Irish Revenue rate calculations, project allocation, and audit-ready exports. It's currently running for a 100-person engineering consultancy with field teams across Ireland.
It doesn't track vehicles or schedule maintenance - that's fleet management software, a different product category - and it doesn't try to be a generic expense tool, because generic expense tools don't understand Irish Revenue band logic. The product is built around the specific compliance shape of grey fleet, and it's narrow on purpose.
If you're handling mileage with spreadsheets and it's becoming a problem, that's the situation OdoHub addresses. Book a 20-minute demo if you'd like to see whether it would fit your team.
OdoHub is a mileage and expenses platform built for Irish and UK firms with field teams. If your organisation struggles with mileage band calculations, project cost allocation, or month-end reconciliation, we'd be happy to show you how it works.