Before You Buy: The Kael Tripton Verdict
By Miles is a pay-per-mile car insurer designed specifically for low-mileage drivers who are systematically overcharged by standard annual-premium insurers. The product consists of a fixed annual cost covering the parked-car risk, plus a per-mile charge for every mile driven, tracked via a plug-in smart device. By Miles is underwritten by RSA Insurance Ltd and achieves a Defaqto 5-star rating. The cost advantage is clearest below approximately 7,000 miles per year. Before buying, calculate your actual annual mileage carefully, understand that the smart device is a required fitting that cannot be removed, and compare the total expected annual cost against comparison-site premiums for equivalent RSA-underwritten cover.
How Pay-Per-Mile Insurance Works
By Miles operates a fundamentally different pricing model from standard annual-premium car insurance. Instead of estimating your annual mileage and charging a fixed premium based on that estimate, By Miles charges two components: a fixed annual cost covering the parked-car risk (the risk of damage to your vehicle while it is stationary - fire, theft, and some accidental damage scenarios) and a variable per-mile charge for every mile you actually drive.
The per-mile charge is tracked via a smart device that plugs into your vehicle's OBD (On-Board Diagnostics) port - a standardised port found in most petrol vehicles manufactured from 1996 onwards and most diesel vehicles from 2001. The device records mileage (not driving behaviour or speed) and transmits the data to By Miles. Your monthly bill reflects the miles driven in that month multiplied by the per-mile rate, plus a proportion of the annual fixed cost.
The financial logic is straightforward. A standard annual-premium insurer charges you for 8,000 miles whether you drive 3,000 or 8,000 miles. With By Miles, a driver who drives only 3,000 miles pays for only 3,000 miles. The break-even point - where By Miles costs approximately the same as a standard annual premium for equivalent cover - is typically around 7,000 miles per year. Below that threshold, By Miles is generally cheaper. Above it, the per-mile charges accumulate to a total that exceeds a standard annual premium for the same profile.
By Miles applies a per-year mileage cap on billing. Above the cap, the per-mile charge no longer applies and the annual cost is fixed at the capped level. This prevents catastrophically high bills in years with unexpectedly high mileage - for example, if you needed to make an extended driving journey for a family emergency. Confirm the specific cap level in your quote documentation, as it varies by policy.
What By Miles Car Insurance Actually Covers
By Miles' comprehensive car insurance is underwritten by RSA Insurance Ltd, a UK-incorporated entity with a long operational history in the UK motor market. RSA was acquired by Intact Financial Corporation in 2021 - Intact is a Canadian insurer with a strong financial profile. The RSA underwriting relationship gives By Miles access to a well-established UK claims operation and the RSA-wide approved repairer network.
The Defaqto 5-star rating on By Miles comprehensive reflects the breadth of cover features, not just the pricing model. Standard inclusions are comprehensive: accidental damage, fire, theft, windscreen repair and replacement, motor legal protection, guaranteed hire car while the vehicle is at an approved repairer, personal accident cover, and uninsured driver protection (NCB protection if hit by an uninsured driver). This is a meaningfully feature-complete policy compared to comparison-site entry-level products.
By Miles' approved repairer network is drawn from RSA's established UK network. For most UK drivers in population centres, approved repairer access is adequate. In rural or remote areas, the nearest approved repairer may require more travel than local alternatives - confirm the network in your area via the By Miles app before purchasing.
Windscreen cover under By Miles comprehensive includes repair with no excess and replacement with a specified excess - confirm the replacement glass excess in your specific quote as it varies by vehicle specification. RSA uses a glass supplier network; non-network glass may be handled differently under the claim.
Motor legal protection is included as standard - covering uninsured loss recovery and legal costs up to the limit specified in the IPID. This is a feature that requires a paid add-on at several comparison-site competitors, making By Miles' inclusion of it at the standard comprehensive level a genuine value differentiator for low-mileage drivers comparing total cost.
The Smart Device: Requirements and Data
The By Miles smart device is a mandatory fitting - the product cannot be purchased without installing the device. It plugs into the OBD port and must remain fitted throughout the policy period. Removing the device without By Miles' authorisation may void cover or constitute a material non-disclosure.
The device records mileage only - By Miles is explicit that it does not monitor driving behaviour (speed, braking, cornering, time of day). This is a meaningful privacy distinction from black-box telematics products such as Marmalade, Hastings YouDrive, or Ingenie, which monitor and score driving behaviour. By Miles' device tracks where you drive to and how far, but not how you drive. The data is used exclusively for billing purposes.
The mileage data and location data collected by the device are subject to By Miles' privacy policy. Consumers who are concerned about location data storage should review the privacy policy before purchase to understand what data is retained, how long it is kept, and who can access it.
If the device malfunctions or is temporarily unavailable (for example, if the vehicle is in for service and the OBD port is needed), By Miles has a process for estimated mileage during device-unavailable periods. Confirm this process before purchase to understand how mileage is billed during device interruptions.
Calculating Whether By Miles Is Right for Your Mileage Profile
The purchasing decision for By Miles starts with honest mileage estimation. Take your odometer reading now and compare against the reading from 12 months ago. If you cannot recall the prior reading, estimate based on your most common journeys: commute miles per week (if any) times 50 working weeks, plus leisure driving estimates.
If your honest estimate is below 5,000 miles per year, By Miles is almost certainly cheaper than a standard annual premium for equivalent 5-star Defaqto cover. At 5,000 to 7,000 miles, the comparison depends on your specific risk profile and what comparison-site alternatives quote. Above 7,000 miles, standard annual premiums from LV=, Aviva, or Direct Line are likely to be more cost-effective for equivalent cover breadth.
The most common error in By Miles purchasing decisions is overestimating how much lower the mileage-based cost will be, based on a prior-year estimate that does not account for life changes. A driver who worked from home for the prior year and estimates 3,000 miles, then returns to an office commute in the By Miles policy year, will find their actual mileage is materially higher than estimated. The mileage cap provides protection against the worst-case scenario, but the per-mile charges will accumulate above what a standard annual premium would have cost.
Who By Miles Car Insurance Suits
Best fit: Home-working drivers with a car primarily used for weekend leisure, retired drivers who drive infrequently, urban drivers who use public transport for most journeys, second-car owners where the second vehicle is rarely used, and anyone whose genuine annual mileage is consistently below 7,000 miles.
By Miles is also an excellent choice for drivers who want 5-star Defaqto RSA-underwritten cover with motor legal protection included as standard, at a total cost that reflects their actual usage rather than a standard insurer's mileage estimate.
Who Should Consider Alternatives
High-mileage drivers: Above 7,000 to 8,000 miles per year, standard annual premiums from LV=, Aviva, or Direct Line will typically be cheaper than By Miles for equivalent cover.
Drivers whose mileage is unpredictable: If your driving pattern is highly variable - 2,000 miles in some years, 12,000 in others - the per-mile model is harder to budget and may produce high-cost years when mileage is elevated. The mileage cap provides some protection, but the uncertainty is a planning challenge.
Drivers whose vehicle is incompatible with the OBD device: Some vehicles - particularly older models, some hybrids, and some EVs - may not have a compatible OBD port or may have port access issues. Confirm device compatibility before purchasing.
Five Things to Check Before You Buy By Miles
- Calculate your actual annual mileage honestly. Use odometer readings, not estimates. An overoptimistic mileage estimate is the primary reason By Miles fails to deliver expected savings. Take the actual reading today and from 12 months ago.
- Confirm OBD port compatibility for your vehicle. Most post-1996 petrol and post-2001 diesel vehicles have an accessible OBD port. EVs and some hybrids may have compatibility issues. By Miles' website provides a vehicle compatibility checker - use it before purchasing.
- Compare the expected annual total cost against comparison-site premiums. Calculate your estimated annual By Miles cost (fixed fee plus per-mile charge times expected mileage) and compare it against at least two comparison-site quotes for equivalent RSA-underwritten 5-star cover. The comparison is the definitive test of value for your profile.
- Understand the mileage cap level and conditions. Confirm the specific mileage cap in your quote documentation. Understand the conditions under which it applies and whether there are any exclusions (for example, miles driven abroad).
- Read the data privacy policy for the smart device. By Miles collects mileage and location data. Review the privacy policy to understand data retention periods, sharing arrangements, and your rights to request deletion before committing.
Related Guides
Editorial disclaimer: Kael Tripton is an independent editorial publisher. We do not receive commission, referral fees or payment from any insurer featured on this page. This article is a pre-purchase editorial analysis, not a personal recommendation. Insurance suitability depends on your individual circumstances. Always read the full policy wording and IPID before purchasing. If you need personalised advice, consult an FCA-authorised insurance broker.
Frequently Asked Questions
How does By Miles calculate my monthly bill?
Your By Miles bill has two components. The first is a fixed annual charge covering the parked-car risk (fire, theft, and some accidental damage while the vehicle is stationary), divided into equal monthly payments. The second is a variable per-mile charge for every mile you actually drive in that month, tracked by the smart device plugged into your vehicle's OBD port. A mileage cap applies annually - above the cap threshold, no additional per-mile charges accrue for the rest of that policy year. The specific fixed fee, per-mile rate, and mileage cap are disclosed in your quote documentation and vary by risk profile and vehicle.
What type of vehicle does the By Miles smart device work with?
The By Miles smart device plugs into the OBD (On-Board Diagnostics) port. Most petrol vehicles manufactured from 1996 onwards and most diesel vehicles from 2001 onwards have an OBD port. Some electric vehicles, older vehicles, and certain hybrid models may have compatibility issues due to port location, port type, or vehicle management system design. By Miles provides a vehicle compatibility checker on its website. Confirm compatibility for your specific vehicle registration before purchasing - if the device cannot be fitted, the By Miles product cannot be used.
Does By Miles monitor my driving behaviour?
No. By Miles explicitly collects mileage and location data only - it does not monitor speed, acceleration, braking, cornering, or time of day. This distinguishes it from black-box telematics products such as Marmalade, Ingenie, or Hastings YouDrive, which monitor and score driving behaviour as a basis for premium adjustments. The By Miles device is used solely for billing (tracking how many miles you drive) rather than for behavioural risk assessment. Mileage and location data are subject to By Miles' privacy policy - review this before purchase.
Sources
ABI Motor Insurance Premium Tracker Q4 2025 (abi.org.uk) • Financial Ombudsman Service Annual Complaints Data 2022/23 (financial-ombudsman.org.uk) • FCA Financial Services Register (register.fca.org.uk) • Defaqto Star Ratings 2026 (defaqto.com) • Financial Services Compensation Scheme (fscs.org.uk) • Gibraltar Financial Services Commission (fsc.gi)
