What Does Speed Cost Per Mile? Fuel at 60 vs 68 mph

A diesel van uses 14.5% less fuel per mile at 60 mph than at 68 mph, according to the Department for Transport. If your van costs 25.2p a mile at 68 mph, it costs about 21.5p at 60 mph, a saving of 3.7p a mile. Apply the same percentage to your own cost per mile.

How much does speed cost in fuel?

Speed costs you a percentage of your fuel per mile, and the percentage grows as the speeds get higher. The Department for Transport (DfT) publishes fuel consumption curves in its TAG data book (v2.03, May 2026, Table A1.3.8, source). They show how much less fuel per mile a vehicle uses at a lower 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	n/a	n/a	n/a	14.5%	20.0%	14.9%
Petrol van	n/a	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%

Read the table as “fuel per mile is this much lower at the second speed than at the first”. Diesel van 68 to 60 mph, 14.5%, means the van uses 14.5% less fuel for every mile at 60 mph than for every mile at 68 mph.

The curves model fuel against average speed. The diesel van curve is valid up to 68 mph, the petrol van curve up to 74 mph and the car curves up to 80 mph, which is why some cells are blank. We do not quote a diesel van figure above 68 mph.

How do you work out the extra cost per mile?

You work out the extra cost by multiplying your cost per mile at the higher speed by the DfT percentage. The method has three steps:

1. Start with your cost per mile at the faster speed. Use your own fuel figure or the formula in diesel cost per mile.
2. Multiply it by the percentage in the table. That is the pence per mile you would save at the lower speed.
3. Subtract that from your starting figure to get the cost per mile at the lower speed.

The table gives percentages for specific pairs of speeds. Use the pair that matches your vehicle, and keep the starting speed the same as the one in the pair. We do not have a DfT figure for every speed, and we do not make up the gaps.

What is the worked example for a diesel van?

Say a diesel van costs 25.2p a mile at 68 mph. That is 36 mpg at the diesel price of 199.22p a litre in the Department for Energy Security and Net Zero (DESNZ) weekly road fuel prices for the week of 26 October 2026.

Average speed	Fuel per mile vs 68 mph	Cost per mile	Extra versus 60 mph
68 mph	Baseline	25.2p	+3.7p
60 mph	14.5% lower	21.5p	None
56 mph	20.0% lower	20.2p	-1.4p

At 60 mph: 25.2p x 14.5% = 3.65p saved, so 21.5p. At 56 mph: 25.2p x 20.0% = 5.04p saved, so 20.2p. The extra at 68 mph versus 60 mph is 3.7p a mile. The 56 mph row against 60 mph is worked from unrounded figures, which is why 21.5p less 20.2p shows as 1.4p.

We have not shown 62 or 65 mph for the diesel van in this table. The DfT figure for 65 to 56 mph is 14.9%, which uses a different starting speed. Use it only if 65 mph is your starting point: 25.2p at 65 mph becomes 21.4p at 56 mph.

What does that mean over a year?

Over a year it depends on how many of your miles are driven at the higher speed. At 3.65p a mile saved, a van doing 20,000 miles a year with every mile at 68 mph rather than 60 mph would spend about £730 more on diesel.

Very few vans spend every mile at 68 mph. Suppose 30% of the miles are at that speed, and the rest are slower roads where a cap changes nothing. That is 6,000 miles x 3.65p, about £220 per van per year. Swap the 30% for your own share. Telematics data shows it.

This is why the fleet-wide saving from a speed cap is not a single figure. It depends on how much of your driving happens above the cap. Our page on fuel savings from speed limiters goes into the wider case.

What about petrol vans and cars, or 70 mph?

For petrol vans and cars you can use the same method and the 70 mph columns. A petrol van costing 24.7p a mile at 70 mph (32 mpg, 174.07p a litre, DESNZ week of 26 October 2026) uses 16.1% less fuel per mile at 60 mph. That is 20.7p, a saving of 4.0p a mile. At 62 mph the DfT figure is 13.7%, so 21.3p.

For a diesel car, 70 to 60 mph is 9.6% and 80 to 70 mph is 12.3%. A petrol car is 8.9% and 12.7%. Apply them to your own cost per mile in the same way. Our petrol cost per mile article has the table to find your starting figure.

For a diesel van there is no DfT figure at 70 mph, because the curve stops at 68 mph. If you want the cost per mile at 70 mph for a diesel van, measure it from your own telematics and fuel records.

Is there a speed where fuel use per mile is lowest?

Yes, and it is well below motorway speed. The DfT curves put the most economical speed at about 39 to 40 mph for a diesel van, about 49 for a petrol van, about 45 for a diesel car and about 50 for a petrol car. Fuel per mile rises on either side of that.

Above the economical speed, every mile per hour costs more fuel per mile than the one before. The speed and fuel tool lets you enter your own vehicles and see the saving from a cap.

Where can you see this week’s cost per mile?

The live figure is on our fleet cost index, which updates every Tuesday after DESNZ publishes. Use it as the starting point for the method above, or substitute your own fuel card data. To take it from fuel to a full vehicle running cost, see how to calculate fleet cost per mile.

Frequently Asked Questions

How much more fuel does a van use at 70 mph than 60 mph?

For a petrol van, the Department for Transport’s curves show 16.1% less fuel per mile at 60 mph than at 70 mph (TAG data book v2.03, May 2026). For a diesel van the curve stops at 68 mph, where the figure to 60 mph is 14.5%.

What is the cost per mile at 70 mph?

It depends on your vehicle and the fuel price. A petrol van at 32 mpg costs 24.7p a mile at 174.07p a litre (DESNZ, week of 26 October 2026). Multiply by the DfT percentage to find the cost at a lower speed.

Is driving at 60 mph really cheaper than 68 mph?

For a diesel van, yes: 14.5% less fuel per mile on the DfT curve. On a van costing 25.2p a mile at 68 mph, that is 21.5p at 60 mph. The saving for the fleet depends on how many miles are driven at the higher speed.

What is the most fuel-efficient speed?

On the DfT curves, about 39 to 40 mph for a diesel van, 49 for a petrol van, 45 for a diesel car and 50 for a petrol car. Above that speed, fuel use per mile rises.

How do I know what share of my miles are above a speed cap?

Telematics or tachograph data shows the time and distance driven above a given speed. Without it, you can estimate from your road mix and check against a trial period.

Cut your fleet’s fuel bill

Your number is your cost per mile at the faster speed, multiplied by the DfT percentage for the cap you are considering. Put your own vehicles into the speed and fuel tool to see it worked out.

A speed cap holds the lower figure on every journey. The Department for Transport’s fuel consumption curves (TAG data book v2.03, May 2026) show a diesel van using 14.5% less fuel per mile at 60 mph than at 68 mph. The saving for your fleet depends on the share of miles you drive above the cap.

AutoKontrol has made speed limiters in Britain since 1985, for vans, cars, HGVs and buses, installed nationwide: we come to you. To have your own saving worked out, book a free consultation or get a quote. To see where the fast miles are in the first place, TrackSpeed combines a speed limiter and GPS tracking in one device, with one installation and one subscription.