Diesel is pushing towards 183p, up more than 40p this month (March 2026 at time of writing) and is experiencing the largest weekly rise since the energy market turmoil of 2022. But while fuel prices grab attention, the biggest and most controllable cost often sits within your own operation.

Driver behaviour, engine idling and undetected fuel fraud collectively represent a level of waste that, at today's prices, no fleet can afford to overlook.

When is fuel consumption at its highest?

Understanding where and when fuel is being consumed is the first step to addressing the cost of fuel. Fuel consumption peaks in three areas: stop-start driving, excessive idling, and high-speed journeys.

Aggressive driving alone can increase fuel use by up to 37%, while idling delivers zero productivity at a constant cost. Even a single vehicle can waste hundreds of pounds per year just sitting still, multiplied across a fleet, the financial impact is substantial.

Transport Research Laboratory (TRL) found that idling accounts for an average of 12% of total engine run time for commercial vehicles in the UK, meaning this isn't an occasional habit, it's a daily measurable drain on fleet finances.

What will reduce fuel consumption?

Smoother driver behaviour is the single most impactful change a fleet can make. Research from the UK Department for Transport found that drivers who received training on fuel-efficient driving techniques achieved reductions of up to 25% in fuel consumption, with further long-term gains over time.

Route optimisation is the second major lever. Fleets that adapt routes based on live traffic and road conditions reduce unnecessary mileage, cut idle time in congestion, and ensure drivers aren't burning fuel on inefficient journeys.

Monitoring and visibility software such as Kinesis provide key data on idling events, driver behaviour and fuel consumption by vehicle, and anomalies in fuel transactions to enable managers to control costs.

The risk nobody is talking about: fuel fraud

Rising prices don't just increase legitimate costs, they increase the incentive and the impact of fuel fraud.

Research commissioned by Shell plc shows that nearly two-thirds (65%) of UK fleet managers now consider fuel-related fraud a significant issue for their business. Almost half (48%) also recognise the need to take further action, with the potential to unlock fuel savings of over 5%.

Without telematics and data insights, detecting and preventing fuel card fraud across a fleet remains a major challenge.

How telematics enables fuel cost mitigation

At Radius, our telematics platform gives managers real-time visibility of every vehicle, turning raw data into actionable insight. Monitoring events like harsh breaking and speeding, enable targeted coaching that delivers measurable fuel savings.

Idle time reporting flags excessive engine-on periods by vehicle, so the problem can be addressed at source rather than absorbed as an ongoing cost.

Our Geo-Plus reporting cross-references vehicle location data with fuel transactions, and identifies anomalies that indicate potential fuel card fraud or misuse, flagging discrepancies before they accumulate into significant losses.

Fuel prices may be outside your control, but the costs of driver behaviour don’t need to be.