70 vs 60 mph Fuel Cost: What It Means for a Van Fleet

Driving at 60 mph instead of 70 mph uses 16.1% less fuel per mile in a petrol van and 9.6% less in a diesel car (Department for Transport). The diesel van curve stops at 68 mph, where 60 mph saves 14.5%. For 20 diesel vans at 199.22p a litre, that is £6,384 a year.

How much less fuel does 60 mph use than 70 mph?

It depends on the vehicle. The Department for Transport (DfT) publishes fuel consumption curves in its TAG data book (v2.03, May 2026, table A1.3.8). This is how much less fuel per mile you use at the lower speed:

Vehicle	70 to 60 mph	68 to 60 mph
Diesel van	not covered	14.5%
Petrol van	16.1%	12.6%
Diesel car	9.6%	7.5%
Petrol car	8.9%	6.8%

The saving is large because air resistance climbs with the square of speed. The last 10 mph on a motorway costs far more fuel than the first 10 mph on an A-road.

Why does the diesel van figure use 68 mph, not 70?

DfT’s diesel van curve is only valid up to 68 mph, so a 70 mph figure for diesel vans would be extrapolation. We do not quote one. For diesel vans we use 68 to 60 mph (14.5%). For petrol vans we use 70 to 60 mph (16.1%), because their curve is valid to 74 mph. For cars we use 70 to 60 mph, because the car curves run to 80 mph.

If your drivers sit at 70, treat the 68 mph figure as a cautious starting point.

What does 70 vs 60 mph cost a van fleet in pounds?

Take 20 diesel vans doing 25,000 miles a year at 36 mpg, with 35% of their miles driven at 68 mph. Diesel is 199.22p a litre in the DESNZ weekly road fuel prices for the week of 26 October 2026. The working goes like this:

1. Fuel per van per year: 25,000 / 36 x 4.54609 = 3,157 litres.
2. Fuel cost per van: 3,157 x £1.9922 = £6,289.
3. Litres driven at 68 mph: 3,157 x 0.35 = 1,105 litres.
4. Litres saved moving those miles to 60 mph: 1,105 x 0.145 = 160 litres.
5. Saving per van: 160 x £1.9922 = £319.
6. Saving for 20 vans: £6,384 a year, 3,204 litres.

At 2.58354 kg CO2e a litre (GHG conversion factors 2026), 160 litres is about 414 kg CO2e a van.

The 35% share is an assumption chosen to make the sum clear. The next section shows how the answer moves with it.

How does the share of fast miles change the saving?

The saving rises in step with the share of miles driven at speed. Same 20 diesel vans, same mileage, mpg and price, 68 to 60 mph at 14.5%:

Share of miles at 68 mph	Litres saved per van	Saving per van	Saving for 20 vans
15%	69	£137	£2,736
25%	114	£228	£4,560
35%	160	£319	£6,384
50%	229	£456	£9,120

A fleet that runs mostly urban rounds will sit near the top of this table and see very little. A fleet that lives on the M6 will sit near the bottom row. Your telematics or tachograph data tells you which you are.

What does it look like for a petrol van or a car?

Using the same method with the 70 to 60 mph figures. Petrol van fleet: 20 vans, 25,000 miles, 32 mpg, 174.07p a litre (DESNZ, week of 26 October 2026), saving 16.1%.

Share of miles at 70 mph	Saving per van	Saving for 20 vans
25%	£249	£4,977
35%	£348	£6,967

For a single diesel car doing 12,000 miles a year at 50 mpg, with 35% of miles at 70 mph, the saving at 9.6% is 37 litres, about £73 a year. Cars save less per vehicle because they use less fuel and the percentage is lower.

Is the saving the same at every stretch of road?

No. These figures treat the curve as a fair guide to fuel per mile at each average speed. Real journeys include traffic, hills, loads and junctions. DfT models fuel against average speed, so the numbers show the effect of cruising slower, not of every individual journey.

That is why the table shows a share of miles. The honest way to size your own saving is to find the share of your fleet’s miles above the speed you would cap at, then apply the percentage for that vehicle type.

Do drivers actually slow down without a cap?

Some will. A target speed written in a policy relies on each driver remembering it on each motorway. A speed limiter sets the maximum, so the 35% in the example moves to the cap without anyone choosing it. In a CE Delft trial for Novem (March 2009), 16 companies fitted limiters to 177 vans and 30 trucks of 3.5 to 12 tonnes for a year and recorded a 5% average fuel saving.

For the full list of other measures, see the fleet fuel savings checklist.

Frequently Asked Questions

How much fuel does driving at 60 mph instead of 70 mph save?

For a petrol van it is 16.1% less fuel per mile, for a diesel car 9.6% and for a petrol car 8.9%, according to the Department for Transport’s curves. DfT’s diesel van curve ends at 68 mph, where 60 mph uses 14.5% less. The saving only applies to the miles you drive at the higher speed.

What is the fuel cost difference between 60 and 70 mph for one van?

For a diesel van doing 25,000 miles a year at 36 mpg with 35% of miles at 68 mph, moving those miles to 60 mph saves about 160 litres, or £319 at 199.22p a litre. Your own mileage, mpg and share of fast miles change the figure. The speed and fuel calculator does the sum for you.

Why not use 70 mph for diesel vans?

DfT’s fuel curve for diesel vans is only valid up to 68 mph. Quoting a 70 mph figure would mean guessing beyond the data. We use 68 mph as the upper speed for diesel vans and say so.

Does driving slower save money if it takes longer?

On fuel alone, yes. Whether it saves money overall depends on your drivers’ hours, delivery windows and cost per hour. Work out the extra minutes on your typical motorway leg against the fuel saved, using your own figures.

Is it only motorway miles that count?

Mostly. Speeds of 60 to 70 mph happen mainly on motorways and some dual carriageways. Urban and 30 mph road miles do not move, which is why the share of fast miles decides the saving.

Cut your fleet’s fuel bill

Put in your own numbers on the speed and fuel calculator. It takes your vehicle type, mileage, mpg and share of miles at speed, and shows the saving at a lower cap using the current DESNZ price.

For a diesel van, the Department for Transport’s fuel consumption curves show 14.5% less fuel per mile at 60 mph than at 68 mph. The more of your miles are driven above the cap, the more of that reaches your bill.

Talk to us. AutoKontrol has made speed limiters in Britain since 1985, for vans, cars, HGVs and buses, and we install nationwide. Book a free consultation or get a quote.