Requirements Specification for a Company Vehicle Booking App: Dublin 2026

The verdict in three sentences

With 120 pool vehicles used 38% of the time, a 1,100-person organisation pays every year for cars that sit idle in the car park. A custom booking app, linked to connected key cabinets and a digital maintenance log, makes it realistic to retire 20 vehicles and save about 90,000 EUR a year. Success depends less on the code than on the requirements specification: priority rules, directory integration and reporting metrics must be written down before the first sprint.

Why shared fleets stay underused

In many Dublin companies, pool cars are still booked through a shared spreadsheet, an email to facilities or a permanent assignment to a department. Teams hold on to "their" car just in case, ghost bookings block slots and nobody knows the real occupancy rate. 38% is a typical figure: a pool vehicle in Ireland costs roughly 4,500 to 6,000 EUR a year all in (depreciation, insurance, servicing, parking, motor tax), whether it moves or not.

Retiring 20 vehicles out of 120 means lifting utilisation to around 46% on the remaining 100, which is modest. Fleet managers generally consider 55 to 65% achievable for a well-run pool without frustrating staff.

Modules to include in the specification

A good specification describes usage, not screens. For a shared fleet, six blocks always come up.

Booking: half-hour slots, recurring bookings for regular rounds, priority rules (on-call staff, executives, field teams), automatic cancellation if the vehicle is not collected within 30 minutes. Identity: single sign-on through the existing directory (Entra ID or Google Workspace), rights by department and licence category. Connected keys: integration with a key cabinet or telematics units that unlock the vehicle by badge or phone. Maintenance log: mileage recorded on return, NCT and service alerts, damage reports with photos. Reporting: utilisation by vehicle, site and department, cost per kilometre, list of vehicles to retire. Compliance: GDPR record of processing, retention period for trips, staff consultation if GPS tracking is switched on, in line with Data Protection Commission guidance.

Budget and timeline

Kolonell's custom application grid applies here: simple from 2,500,000 to 4,000,000 FCFA (3,810 to 6,100 EUR), medium from 4,000,000 to 7,000,000 FCFA (6,100 to 10,670 EUR), complex from 7,000,000 to 15,000,000+ FCFA (10,670 to 22,870+ EUR). Booking with SSO and dashboards usually sits in the medium band; adding key cabinets, GPS and data migration moves the project into the complex band. Specific hardware integrations are quoted separately. A realistic timeline is 10 to 14 weeks, including acceptance testing.

Application maintenance comes in three levels: 35,000, 75,000 or 120,000 FCFA a month (53, 114 or 183 EUR). For a fleet app, the middle level usually covers security updates and small changes. For comparison, off-the-shelf fleet booking SaaS in Ireland typically costs 8 to 15 EUR per vehicle per month as a 2026 order of magnitude, so 11,500 to 21,600 EUR a year for 120 vehicles, with less control over the rules.

Mini case study

Aoife, facilities director of a 1,100-person services company in Dublin, starts with 120 vehicles at 4,500 EUR a year, or 540,000 EUR. She chooses a complex-band app at around 20,000 EUR, plus 5,000 EUR for key units, and middle-level maintenance at 114 EUR a month, about 1,370 EUR a year. After six months of reliable data she finds 20 vehicles used less than 15% of the time and retires them: a gross saving of 90,000 EUR a year. First-year cost: 25,000 + 1,370 = 26,370 EUR. First-year net gain, if the vehicles go at mid-year: 45,000 - 26,370 = 18,630 EUR. From year two, the net gain exceeds 88,000 EUR.

FAQ

Is a custom app better than a fleet booking SaaS?

It depends on your rules. A SaaS at 8 to 15 EUR per vehicle per month works for simple pools, while a custom app pays off when priority rules, directory integration and key hardware are specific to your organisation.

How long before we can retire vehicles?

Allow three to six months of data after go-live. A full quarter is the minimum to smooth out seasonal peaks such as summer field work.

Is GPS tracking required?

No. Mileage on return and badge unlocking are enough to measure use. GPS tracking requires a data protection impact assessment and staff information, which often adds 4 to 6 weeks.

Can we import our current spreadsheet?

Yes, in most cases. Migrating 2 to 3 years of servicing and mileage history takes a few days if the columns are consistent.

What happens when someone returns a car late?

The app alerts the late driver and the next booker, then offers a replacement vehicle. These rules are configured without extra development.

Let's scope your project. We define the modules, the directory and key cabinet integrations and a 10 to 14 week plan with you. Detailed quote within 48 h. WhatsApp +221 77 596 93 33.