Motorists could be paying up to five times more than expected for routine repairs, according to new research from automotive diagnostics specialist Carly.
Its undercover investigation found that a repair expected to cost around £110 was quoted at as much as £672, highlighting significant inconsistencies across UK garages.
Garage pricing gaps exposed
The mystery shop, carried out across 10 garages including independents and main dealers, used the same Seat Ibiza with a known oxygen sensor fault to assess pricing consistency.
While all sites correctly diagnosed the issue, quotes varied widely. A national chain garage in Leeds quoted £672 to replace both oxygen sensors, while main dealers in Stoke-on-Trent and Sunderland quoted £618 and £328 respectively.
In addition to price variation, Carly identified a pattern of upselling, with four of the 10 garages recommending additional work unrelated to the known fault.
These included brake replacements, spark plugs and air-conditioning servicing, potentially adding between £400 and £950 to repair bills without clear justification.
Trust gap impacts aftersales
The investigation was supported by a OnePoll survey of 2,000 UK motorists, which revealed widespread uncertainty around garage pricing.
More than half (52%) of drivers said they either suspect or are unsure if they have been overcharged in the past five years, while 45% said they distrust garages or are uncertain whether quotes are fair.
Over half (56%) believe garages have the upper hand when it comes to repair costs, and four in ten said additional work is often recommended without clear explanation.
Confidence in diagnosing faults also remains low, with 51% of drivers saying they would struggle to identify a serious issue before a breakdown, despite 69% attempting to self-diagnose before visiting a workshop.
Emma Brown, UK growth manager at Carly, added: “What this investigation highlights is a clear information gap between drivers and garages. Many motorists simply don’t have the tools to understand what’s wrong with their car or what a repair should realistically cost before agreeing to work.
Carly’S scanner and app unlock vehicle fault data, live diagnostics, and manufacturer-level coding features to help owners stay in control of their car’s health, costs and performance.
“Carly is designed to close the gap,” said Brown. “By identifying faults early, translating complex diagnostics into plain English, and giving drivers a clear idea of typical repair costs. It’s not about replacing mechanics, but about helping motorists walk into a garage informed, ask the right questions, and feel confident they’re paying a fair price.”
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