Dirt refers to harmful deposits that can form in engines, causing a loss in engine performance. It can build up over time and over a range of driving conditions. Dirt is a well-known issue in car engines.
The critical engine components that dirt affects are the intake valves and fuel injectors in petrol engines and the fuel injectors in diesel engines.
When an engine is affected by dirt the driver may notice a loss of responsiveness, for example the vehicle doesn’t perform as expected when accelerating.
In diesel engines a build-up of dirt in the fuel injectors restricts the flow of fuel causing a reduction in maximum engine power. The loss in power may be felt by the driver as the vehicle may no longer accelerate as quickly as it could when the vehicle was new.
In petrol engines slimy or sooty deposits can build up on the intake valves. The driver may notice a momentary hesitation or loss of responsiveness when accelerating.
BP Ultimate Unleaded and BP Ultimate Diesel are specially formulated to remove existing dirt from these critical engine components and protect against its build up. In fact our tests show that BP Ultimate fuels clean away the majority of dirt in just two tankfuls.*
*Benefits may vary due to factors including vehicle type, condition and driving style.
Our Fuel Economy Testing
BP Ultimate could give up to 21 more miles per tank.* We tested the fuel economy benefit that could be achieved through the use of BP Ultimate fuels as follows:
Fuel economy testing was conducted using vehicles with representative harmful deposits on critical engine components.
A range of vehicles were tested. The vehicles were selected to represent a variety of the types of engine technologies available in the UK. These vehicles were tested using a drive cycle designed to better reflect real life driving than the current EU legislative drive cycle.
After measuring the fuel consumption of each vehicle with the engine in a dirty condition, the vehicles were then fuelled with BP Ultimate and driven. The petrol vehicles were driven for approximately 6,200 miles and the diesel vehicles were driven for approximately 1865 miles. The fuel consumption of each vehicle was then measured again to calculate the fuel economy benefit.
The fuel economy benefit was then converted into a range claim (expressed in terms of more miles per tank) by multiplying the fuel economy benefit by a typical range per tank for UK passenger cars. The expected ranges for petrol vehicles and diesel vehicles are different because diesel fuel contains more energy per unit volume and diesel engine vehicles have lower fuel consumption than similar petrol engine models. The range per tank used for petrol vehicles was 391 miles and the range per tank used for diesel vehicles was 516 miles.
Actual fuel economy benefits achieved may vary depending on vehicle type, condition, engine technology, driving style, road conditions and other factors such as length of journey, climate, tyre pressures and vehicle loading.
In our tests we measured the full fuel economy benefit after ca. 6,200 miles for petrol and ca. 1,865 miles for diesel; however it is possible some benefits could be achieved sooner.
BP Ultimate Unleaded has a higher octane (97 RON minimum) than the minimum 95 RON required by law for petrol in the UK. For petrol vehicles that have been designed to take advantage of a higher octane fuel those drivers could achieve some instantaneous benefits although this will also be influenced by their driving style.
BP Ultimate Unleaded also contains a friction modifier component which over the full ca. 6,200 mile test improves the lubrication of the upper cylinders in the engine. This friction modifier can also contribute to improved engine efficiency and therefore fuel economy.
For the vast majority of diesel vehicles (those with direct injection) any fuel economy benefit is primarily derived from the removal of dirt. Since BP Ultimate Diesel cleans away the majority of dirt in direct injection diesel engines in two tankfuls, the fuel economy benefit of up to 21 more miles per tank* should be achievable in two tankfuls.
*Based on engines tested in dirty vs clean condition; in dirty condition expected miles per tank 391 (petrol) or 516 (diesel); for Ultimate Unleaded vs RON95. Benefits achieved over time and may vary due to factors including vehicle type, condition and driving style.