The verdict in three sentences
A pool of 70 vehicles used at 45 % means about 38 cars sit idle every working day, while leases, insurance and maintenance keep running. A custom booking app, priced between 25,000 and 55,000 GBP in London in 2026, makes demand visible, shares cars across sites and recharges each department. The realistic target is to remove 15 vehicles from the fleet, worth roughly 120,000 GBP a year, with a project delivered in 10 to 12 weeks.
What an under-used pool car really costs
Before pricing the app, price the waste. The total cost of ownership (TCO) of a pool car is far more than the lease. The figures below are 2026 estimates for Greater London, where parking and congestion-related costs weigh heavily.
| Annual cost per vehicle | City EV | Hybrid hatchback | Light van |
|---|---|---|---|
| Contract hire (36 months, 12,000 miles/year) | 4,200 GBP | 4,600 GBP | 5,200 GBP |
| Fleet insurance | 1,100 GBP | 1,200 GBP | 1,500 GBP |
| Maintenance and tyres outside contract | 350 GBP | 450 GBP | 650 GBP |
| Parking bay or permit | 1,800 GBP | 1,800 GBP | 2,000 GBP |
| Admin (PCNs, charge cards, ULEZ checks) | 400 GBP | 450 GBP | 500 GBP |
| TCO excluding energy | 7,850 GBP | 8,500 GBP | 9,850 GBP |
With an average TCO close to 8,000 GBP per vehicle, 15 surplus cars cost about 120,000 GBP a year. Fuel and charging are excluded because they follow miles driven, not fleet size.
The features that shrink the fleet, and what they cost
A shared calendar is not enough. What reduces the fleet is data: real occupancy per site, peak slots and ghost bookings that are never collected. Here is a typical breakdown with 2026 London market ranges.
| Module | Scope | 2026 market range (GBP) |
|---|---|---|
| Booking and planning | Slots, multi-site, rules per category, mobile | 6,000 to 12,000 |
| Connected keys | Key cabinets or telematics, unlock by badge or app | 5,000 to 11,000 (hardware excluded) |
| Maintenance logs | Mileage alerts, MOT, damage reports | 3,000 to 6,500 |
| Department recharging | Cost centres, monthly finance export | 3,500 to 7,500 |
| Dashboards | Occupancy, no-shows, fleet size forecast | 4,000 to 9,000 |
| IT integrations | Microsoft Entra ID SSO, HR directory, ERP | 3,500 to 9,000 |
| Total project | 25,000 to 55,000 |
Connected-key hardware is extra: a 20-slot electronic key cabinet usually costs 3,500 to 7,000 GBP, a telematics box 130 to 260 GBP per vehicle plus 7 to 13 GBP a month. For reference, Kolonell's grid for a medium-complexity business app is 4,000,000 to 7,000,000 FCFA (6,100 to 10,670 EUR), and 7,000,000 to 15,000,000 FCFA (10,670 to 22,870 EUR) for a complex build with telematics and multiple integrations.
A 10 to 12 week plan
The timeline holds if facilities and IT sign off quickly. Weeks 1 to 2: scoping, fleet inventory, priority rules (sales, engineers, executives). Weeks 3 to 4: prototypes tested with five users. Weeks 5 to 9: development in increments, with a pilot site from week 7. Weeks 10 to 12: acceptance testing, administrator training, phased roll-out to other sites.
The single most profitable rule is auto-cancellation: a car booked and not collected within 30 minutes is released. In pools we have seen, ghost bookings often block 10 to 20 % of slots.
Mini case study
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Emma, head of facilities at a 900-employee engineering firm in London (illustrative example), manages 70 vehicles across three sites. After three months of data, the app shows a 62 % peak on Tuesday mornings and a 45 % average. Targeting 70 % occupancy would need about 45 cars, but she keeps a buffer and removes 15.
Calculation: 15 vehicles x 8,000 GBP TCO = 120,000 GBP saved per year. For a 42,000 GBP project, plus 5,000 GBP of key cabinets and 6,000 GBP of annual maintenance, payback comes in about 5 months.
FAQ
How much does a pool car booking app cost in 2026?
In London, expect 25,000 to 55,000 GBP for a custom app with booking, maintenance and recharging. Connected-key hardware is extra, often 3,500 to 7,000 GBP per cabinet.
Why not buy an off-the-shelf fleet SaaS?
Fleet SaaS tools cost around 10 to 25 GBP per vehicle per month, or 8,400 to 21,000 GBP a year for 70 cars. They fit standard rules; custom becomes worthwhile once recharging, SSO and priority rules are specific to you.
How many vehicles can be removed?
With 45 % occupancy and a 65 to 70 % target, a 15 to 25 % fleet reduction is a common estimate. You need at least 8 to 12 weeks of reliable data before deciding.
Do all vehicles need telematics?
No, a key cabinet is enough to start on a central site. Telematics, at 130 to 260 GBP per vehicle, helps for unstaffed sites and for measuring real mileage.
What about UK GDPR?
Employee location data is regulated: run a DPIA, inform staff, keep trip history for a limited period (often 2 months) and disable tracking outside working hours.
Let's scope your project. Send us your fleet size, sites and booking rules, and we will return a scope, an indicative budget and a 10 to 12 week plan. Detailed quote within 48 h. WhatsApp +221 77 596 93 33.
Mohamed Bah
Fondateur, Kolonell
Passionate about digital and entrepreneurship in Africa, Mohamed has been helping Sénégalese businesses with their digital transformation since 2020. Founder of Kolonell, he believes every SME deserves a professional and accessible online présence.
