Which speed saves the most fuel?
Driving at a steady, lower speed on fast roads is the driving technique that saves the most fuel. Department for Transport figures show a diesel van uses 14.5% less fuel per mile at 60 mph than at 68 mph, and a diesel car 9.6% less at 60 than at 70. Cars and vans are most economical at about 40 to 50 mph.
Source: DfT TAG data book v2.03 (May 2026), Table A1.3.8. Calculator uses the DESNZ diesel price for the week of 26 October 2026.
What a speed cap saves your fleet
Your vehicles, your miles, this week's pump price. Only the miles you drive above the cap change.
Capping at 60 mph uses less fuel on every fast mile.
Get a quoteFuel only. The saving applies DfT's per-mile difference between the two speeds to the share of miles you set. Vans are covered up to 68 mph (diesel) and 74 mph (petrol), cars up to 80 mph: the limits of DfT's published curves. HGVs are limited to 56 mph by law and DfT's HGV curves stop at 52 mph, so talk to us for HGV figures.
How much more fuel does each extra mile an hour use?
Each figure is the extra fuel per mile compared with that vehicle's most economical speed on DfT's curves. A dash means the speed is outside the range DfT publishes for that vehicle.
| Vehicle | Best speed | 30 mph | 40 mph | 45 mph | 50 mph | 55 mph | 60 mph | 62 mph | 65 mph | 68 mph | 70 mph | 75 mph | 80 mph |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Diesel van | 39 mph | +5% | +0% | +2% | +6% | +13% | +23% | +28% | +35% | +44% | - | - | - |
| Petrol van | 49 mph | +24% | +5% | +1% | +0% | +2% | +8% | +11% | +17% | +23% | +29% | - | - |
| Diesel car | 45 mph | +7% | +1% | +0% | +1% | +3% | +7% | +8% | +12% | +15% | +18% | +26% | +34% |
| Petrol car | 50 mph | +15% | +4% | +1% | +0% | +1% | +3% | +5% | +8% | +11% | +14% | +21% | +30% |
| Rigid HGV | 44 mph | +7% | +0% | +0% | +1% | - | - | - | - | - | - | - | - |
| Articulated HGV | 52 mph | +23% | +9% | +4% | +1% | - | - | - | - | - | - | - | - |
| Bus or coach | 49 mph | +15% | +3% | +1% | +0% | - | - | - | - | - | - | - | - |
How much fuel does a lower speed save per mile?
The per-mile saving from common speed caps. These are the miles a limiter changes: time spent on the motorway or dual carriageway at the higher speed.
| Vehicle | 80 to 70 mph | 70 to 60 mph | 70 to 62 mph | 68 to 60 mph | 68 to 56 mph | 65 to 56 mph |
|---|---|---|---|---|---|---|
| Diesel van | - | - | - | 14.5% | 20.0% | 14.9% |
| Petrol van | - | 16.1% | 13.7% | 12.6% | 16.4% | 11.5% |
| Diesel car | 12.3% | 9.6% | 8.0% | 7.5% | 10.1% | 7.2% |
| Petrol car | 12.7% | 8.9% | 7.6% | 6.8% | 8.8% | 6.0% |
Why a fleet saves less than the per-mile figure
A limiter only changes the miles driven above its setting. If a third of a van's miles are on the motorway at 68 mph, a 60 mph cap saves 14.5% on that third, which is about 4.8% of the whole fuel bill. That is why trials across whole fleets report smaller numbers than the per-mile curves, and why the share of fast miles matters more than anything else in the calculator.
Per mile, diesel van at 56 mph against 68
DfT's published fuel curve for diesel vans (TAG data book v2.03, Table A1.3.8).
Average across 207 vans and trucks
One-year independent trial with 16 companies running 177 vans and 30 trucks of 3.5 to 12 tonnes (CE Delft for Novem, 2009).
Better fuel economy, 19 utility vehicles
Six-month trial of AutoKontrol's Rev.Control on vans, tippers and pick-ups, most towing trailers: 4.42 mpg better on average (Transport Engineer, 25 October 2012).
Which driving techniques save the most fuel?
- Hold a steady, lower speed on fast roads. This is the biggest single lever, because air resistance rises with the square of speed. The tables above show how much.
- Accelerate smoothly and change up early. Hard acceleration burns fuel that braking then throws away.
- Read the road ahead. Easing off early for junctions and traffic keeps momentum and saves braking.
- Don't idle. An engine running while parked uses fuel and goes nowhere.
- Check tyre pressures and carry less weight. Under-inflated tyres and unneeded load both add rolling resistance.
The first is the one a fleet can guarantee. Driver training fades; a speed limiter holds the setting on every journey, for every driver.
Use this data
Journalists, analysts and fleet teams can quote or chart these figures. Please credit AutoKontrol and link to this page.
AutoKontrol (2026). Speed and fuel: fuel use by speed for UK cars, vans, HGVs and buses. Calculated from DfT TAG data book v2.03, Table A1.3.8. https://autokontrol.com/en/data/speed-and-fuel/
Guides
- Which Driving Technique Can Save Fuel? Speed Comes First
- What Does Fuel Efficient Driving Achieve? Costs, CO2 and Wear
- 70 vs 60 mph Fuel Cost: What It Means for a Van Fleet
- Fuel Efficient Driving for Fleets: Why Training Fades
- Fleet Fuel Savings Checklist: 8 Ways to Cut Fuel Costs
- Speed Limiter or Telematics or Training: Which Cuts Fuel?
- Fuel Savings from Speed Limiters: Data, Studies & Real Numbers
Questions people ask
Which driving technique can save fuel?
Driving at a steady, lower speed on fast roads saves the most, because fuel use climbs steeply above about 50 mph. DfT's fuel curves show a diesel van uses 14.5% less fuel per mile at 60 mph than at 68 mph. Smooth acceleration, reading the road ahead, not idling, correct tyre pressures and carrying less weight all help too.
What is the most fuel efficient speed?
On DfT's curves, cars are most economical at about 45 to 50 mph and vans at about 39 to 49 mph. Above that, every extra mile an hour costs more fuel per mile, and the rise gets steeper the faster you go.
How much fuel does a speed limiter save?
It depends on how many of your miles are driven above the limit. Per mile, a diesel van at 60 mph uses 14.5% less fuel than at 68 mph (DfT). Across a whole fleet, an independent one-year trial of 177 vans and 30 trucks measured a 5% average saving (CE Delft for Novem, 2009). A six-month trial of AutoKontrol's Rev.Control on 19 utility vehicles measured 24.72% better fuel economy (Transport Engineer, 2012).
How much more fuel does 80 mph use than 70 mph?
On DfT's curves a petrol car uses 12.7% less fuel per mile at 70 mph than at 80 mph, so 80 mph costs about a seventh more fuel for every mile.
How fast can HGVs go, and do the curves cover them?
HGVs over 3.5 tonnes must be limited to 56 mph (90 km/h) by law. DfT publishes its HGV and bus curves up to 85 km/h (52 mph), so this page does not model HGV speeds above that. We can work through HGV savings with you using your own telematics data.
Why do your figures differ from other websites?
Most quote one figure with no source. We use the Department for Transport's published curves, show which vehicle and which speeds each figure applies to, and list the trials separately so you can see the range.
Sources and method
- DfT TAG data book v2.03 (May 2026), Table A1.3.8. Fuel consumption against average speed, L = a/v + b + c.v + d.v². We use the published parameters only inside each vehicle's published speed range and only as ratios between speeds
- CE Delft for Novem (2009), Limitation to order: results of trials with speed limiters on vans and light trucks. 16 companies, 177 vans and 30 trucks of 3.5 to 12 tonnes, one year, 5% average fuel saving
- Transport Engineer (25 October 2012), Speed tests improve fuel economy for utilities firm. 19 vehicles, six months, AutoKontrol Rev.Control, 4.42 mpg or 24.72% better fuel economy
- Department for Energy Security and Net Zero, Weekly road fuel prices. Diesel price in the calculator: 199.2p a litre, week of 26 October 2026
- DESNZ Greenhouse gas reporting: conversion factors 2026. Diesel 2.58354 and petrol 2.075 kg CO2e a litre (average biofuel blend)
Work it out in the calculator above.
DfT's fuel curves show a diesel van at 60 mph uses 14.5% less fuel per mile than at 68 mph.
Free consultation: we go through your numbers and show what limiting would save.
Talk to us about cutting your fuel bill
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