With petrol now at 151p per litre and diesel approaching 188p, the cost of running a car has never felt more painful. But before you resign yourself to the expense, it is worth knowing that most drivers are leaving significant fuel economy on the table through habits that are easy to change. Improving your MPG — miles per gallon — by even 10-15% can save you hundreds of pounds a year without spending a penny on modifications.
What is MPG and why does it matter?
MPG stands for miles per gallon — a measure of how far your car travels on a given amount of fuel. The higher your MPG, the more economical your car is. A car achieving 40 MPG will travel 40 miles on one gallon (4.55 litres) of fuel. At current petrol prices, that gallon costs around 71p per mile. Improve to 50 MPG and that drops to 57p per mile — a saving of 14p on every mile you drive.
How to improve your MPG — 15 proven tips
1. Slow down on the motorway
This is the single biggest MPG improvement available to most drivers. Aerodynamic drag increases with the square of speed — driving at 80mph uses roughly 25% more fuel than driving at 70mph. Sticking to 70mph on motorways and 50-60mph on A-roads where safe to do so can dramatically improve fuel economy. According to the AA, dropping from 80mph to 70mph can improve fuel economy by up to 25%.
2. Accelerate gently
Harsh acceleration is the enemy of fuel economy. Every time you floor the accelerator, you inject a large burst of fuel into the engine. Smooth, progressive acceleration uses far less fuel. Try to anticipate the road ahead and accelerate gradually rather than in sharp bursts.
3. Read the road and brake less
Every time you brake, you waste the kinetic energy your engine worked to create. Instead of braking hard and then accelerating again, try to maintain a steady speed by reading the road ahead. Lift off the accelerator early when approaching junctions, roundabouts or traffic lights — modern cars use virtually zero fuel when decelerating in gear.
4. Keep your tyres properly inflated
Under-inflated tyres increase rolling resistance, forcing your engine to work harder. Check your tyre pressures monthly and before long journeys. The correct pressures are in your car's handbook and often on a sticker inside the driver's door. Some manufacturers recommend slightly higher pressures for motorway driving or when carrying a full load. (source)
5. Change gear at the right time
Driving in too low a gear at high revs wastes fuel. Modern cars often have a gear change indicator on the dashboard. As a general rule, change up at around 2,000 RPM for diesel engines and 2,500 RPM for petrol. Skip gears where possible — going from 3rd to 5th on an empty road is perfectly fine and saves fuel.
6. Remove unnecessary weight
Every extra 50kg in your car increases fuel consumption by around 2%. Clear out your boot — roof boxes, bike racks and heavy items all reduce efficiency. Remove roof bars when not in use, as they create aerodynamic drag even when empty.
7. Turn off air conditioning when you don't need it
Air conditioning can increase fuel consumption by 8-10% in city driving. At lower speeds, opening a window is more efficient. At motorway speeds however, the aerodynamic drag from an open window can exceed the fuel cost of running the AC — so use AC at higher speeds and open windows in town.
8. Plan your route to avoid traffic
Stop-start traffic is devastating for fuel economy. Use navigation apps to avoid congestion where possible. A slightly longer route at a steady speed will almost always use less fuel than a shorter route through heavy traffic.
9. Service your car regularly
A well-maintained engine runs more efficiently. Fresh engine oil, clean air filters, and new spark plugs all contribute to better fuel economy. A clogged air filter alone can reduce MPG by up to 10%. Follow your manufacturer's service schedule.
10. Consider your fuel grade
Some manufacturers recommend premium unleaded (E5) for certain engines. Using the correct fuel grade for your car can improve performance and sometimes economy. Check your handbook — if your car is designed for regular unleaded, premium fuel will not improve MPG meaningfully.
11. Use cruise control on motorways
Maintaining a perfectly steady speed is something humans struggle with — we naturally speed up and slow down constantly. Cruise control eliminates this variation and typically improves motorway fuel economy by 5-10%.
12. Warm up efficiently
Engines are less efficient when cold. Avoid very short journeys where the engine never reaches operating temperature — these trips have disproportionately high fuel costs per mile. If possible, combine short errands into one trip so the engine stays warm throughout.
13. Park in the sun in winter
A warmer engine reaches operating temperature faster. Parking in direct sunlight during winter means your engine starts at a slightly higher temperature and warms up more quickly, reducing the time spent in inefficient cold-running mode.
14. Avoid idling
Modern fuel injection engines use essentially zero fuel when switched off, but burn fuel continuously when idling. If you are waiting for more than 30 seconds — at a level crossing, in a queue, or picking someone up — switching the engine off saves fuel and is legal in the UK.
15. Check your MPG regularly
Most modern cars display real-time and average MPG in the instrument cluster. Monitoring this regularly raises your awareness of how different driving styles affect consumption. Set yourself a target and try to beat it.
How much can you actually save?
For a driver covering 10,000 miles per year in a car achieving 35 MPG on petrol at 151p per litre, annual fuel costs are around £1,980. Improving to 42 MPG through better driving habits reduces that to £1,650 — a saving of £330 per year, with no outlay whatsoever.
The other side of the equation — where you buy fuel
Improving your MPG is one way to reduce fuel costs. The other is making sure you pay as little as possible per litre. Use Save at the Pump to find the cheapest fuel station near you, updated hourly from official Government data. Combined with the MPG tips above, you could save over £500 a year on fuel.
The science behind MPG improvement — what actually works
Studies from the Energy Saving Trust confirm that smoother driving alone can improve fuel economy by up to 15%, saving over £200 a year for an average driver. The key insight is that most fuel is wasted not in steady cruising but in unnecessary acceleration and braking. Every time you brake unnecessarily, you are throwing away kinetic energy that took fuel to create. Every time you accelerate harshly from a standstill, you burn significantly more fuel than a gradual pull-away.
Research consistently identifies three driving behaviours as the most impactful on fuel consumption:
- Speed: Dropping from 70mph to 60mph on a motorway typically improves fuel economy by 10-15%. Above 55mph, aerodynamic drag increases sharply. Every 10mph above 55mph costs roughly 7-14% more fuel.
- Smoothness: Anticipating traffic and coasting to junctions rather than accelerating then braking can improve efficiency by 10-15% in urban driving.
- Tyre pressure: Every 10 PSI of under-inflation increases fuel consumption by approximately 3%. A car with all four tyres 10 PSI low is effectively paying 3% more for every litre of fuel.
How much money can you actually save?
For a driver covering 7,100 miles per year in a 40 MPG car at current prices of 158.74p per litre, the annual fuel bill is approximately £1,277. Here is what different levels of improvement save:
| Improvement | New MPG | Annual saving |
|---|---|---|
| 5% improvement (easy wins) | 42 MPG | £61 |
| 10% improvement (consistent effort) | 44 MPG | £116 |
| 15% improvement (Energy Saving Trust benchmark) | 46 MPG | £166 |
| 25% improvement (committed effort) | 50 MPG | £255 |
MPG improvement combined with finding cheaper fuel
The biggest savings come from combining efficient driving with finding the cheapest nearby station. A driver doing 7,100 miles per year in a 40 MPG car using 840 litres of fuel annually:
- Improving efficiency by 15% saves approximately 126 litres — worth £166 at current prices
- Finding fuel consistently 8p per litre cheaper saves a further £67 per year
- Combined saving: approximately £233 per year with no lifestyle changes
Use our live fuel price map to find the cheapest station near you, updated every hour from official Government data. Our fuel cost calculator shows exactly how much you spend annually at your current MPG and local prices.
Advanced techniques — hypermiling
Drivers who want to go further than standard efficiency tips can explore hypermiling — the practice of maximising fuel economy through advanced driving techniques. Dedicated hypermilers regularly achieve 30-50% above their car's official MPG figure. Read our complete UK hypermiling guide for the full range of techniques.
How to check if your improvements are working
The most accurate way to measure your actual MPG improvement is the brim-to-brim method. Fill your tank completely and note the mileage. Drive normally. Fill up again completely and note the litres added and new mileage. Your actual MPG is: (miles driven divided by litres added) multiplied by 4.546.
Many modern cars display a live or average MPG figure on the dashboard. This is a useful guide but tends to be slightly optimistic. The brim-to-brim calculation gives you the true figure.
Related guides
- Find the cheapest fuel near you — combine better MPG with cheaper fuel for maximum savings
- Why fuel prices rise fast but fall slowly — understanding the market
- Check if your car is compatible with E10 petrol
- Hypermiling — how to double your MPG
- UK fuel price chart — track petrol prices over time
- Calculate how much you could save by improving your MPG