Frequently Asked Questions
Everything you need to know about Fuel Smarter — how it works, how accurate it is, and what makes it different from other fuel calculators.
Fuel Smarter is a free online fuel cost calculator that helps drivers understand the true cost of any car journey. Unlike basic calculators that just divide distance by MPG, Fuel Smarter uses real Google Maps route data, breaks journeys down by road type, applies speed-based efficiency adjustments, uses live local fuel prices, and shows CO2 emissions alongside cost. It supports 30+ countries and requires no account or signup.
Yes — completely free. No account required, no signup, no premium tier, and no hidden costs. The tool will always be free to use.
Most fuel calculators simply divide distance by MPG and multiply by fuel price. Fuel Smarter goes further — it uses real Google Maps routes, breaks journeys down by road type (urban driving uses fuel very differently to motorway cruising), adjusts for driving speed, shows a three-way speed comparison so you can see exactly what you'd save at the speed limit, calculates CO2 emissions, and supports 30+ countries with correct local units and live prices.
No personal data is stored. Route calculations are cached for 24 hours to improve performance, and fuel prices are cached for 6 hours. No personal information, vehicle details, or journey history is stored or associated with you personally. See our Privacy Policy for full details.
Fuel Smarter uses the Google Maps Routes API to calculate the real driving distance between your origin and destination, and breaks it down by road type. It then applies your vehicle's real-world fuel economy, current local pump prices, and a speed-based efficiency adjustment to calculate the exact fuel cost for three scenarios: your speed, the national speed limit, and 10mph below the limit.
Different road types have very different fuel consumption characteristics. Urban driving involves frequent stopping and starting, which is far less efficient than steady motorway cruising. By splitting your journey into road types, Fuel Smarter applies the correct efficiency factor to each leg rather than using a single average — making the cost calculation significantly more accurate.
Driving speed has a significant impact on fuel consumption — driving at 80mph instead of 70mph typically reduces fuel economy by 10-15%. Fuel Smarter shows your actual speed, the national speed limit, and 10mph below the limit so you can see exactly how much you would save or spend at each speed, in both cost and CO2 terms.
Enter your vehicle's make, model, year, and optionally the engine or trim level. Fuel Smarter estimates your real-world fuel economy based on owner data — not the official manufacturer figure, which is typically 10-20% higher than what drivers actually achieve. You can also enter your MPG manually if you know it from your own experience.
Fuel prices are estimated based on current market data and updated regularly. They reflect national averages — your local forecourt may be a few pence per litre different. You can edit the fuel price field to enter your exact local price for a more accurate result. Supermarkets are typically 4-6p per litre cheaper than branded forecourts.
Fuel Smarter supports 30+ countries including the United Kingdom, United States, Canada, Australia, Germany, France, Spain, Italy, Netherlands, Belgium, Portugal, Poland, Sweden, Norway, Denmark, Switzerland, Austria, Ireland, Japan, China, India, Brazil, Mexico, South Africa, New Zealand, Singapore, UAE, Saudi Arabia, Turkey, and Russia. Each country uses correct local units, currency, speed limits, and fuel type names.
Both — Fuel Smarter automatically uses the correct units for your selected country. UK and US users see miles and mph. Most other countries see kilometres and km/h. Fuel economy is shown in MPG for UK and US, L/100km for European and Australian users, and km/L for Japanese and Indian users.
Most petrol cars achieve their best fuel economy between 45-60mph (70-100km/h). Above that, aerodynamic drag increases rapidly — at 70mph you are pushing through 36% more air resistance than at 60mph. Efficiency drops significantly above 70mph, which is why dropping from 80mph to 70mph on a long motorway journey can save a meaningful amount in both fuel cost and CO2 emissions.
Petrol produces approximately 2.31kg of CO2 per litre burned. Diesel produces approximately 2.68kg per litre. Fuel Smarter calculates the exact CO2 for your journey and shows relatable equivalents — like how many trees would be needed to absorb it, or the equivalent number of smartphone charges.
Diesel is currently around 32p per litre more expensive than petrol in the UK — one of the largest gaps in Europe. The Competition and Markets Authority has found evidence of slow price adjustment in diesel. The UK government's Fuel Finder scheme, mandatory since February 2026, is designed to improve price transparency and increase competition between forecourts.
The UK Government's Fuel Finder scheme requires all forecourts to report prices within 30 minutes of any change. Apps using this data show live prices near you. Supermarket forecourts typically offer petrol 4-6p per litre cheaper than branded stations. Prices also tend to be lower mid-week (Tuesday/Wednesday) than at weekends.