What Each 0.5 mpg Is Worth to an HGV Fleet

An extra 0.5 mpg is worth £3,412 a year to an artic at 7.9 mpg doing 60,000 miles, and £5,687 at 100,000 miles. An extra 1 mpg is worth £6,441 to £10,734. These use the diesel price for the week of 26 October 2026, 166.02p a litre before VAT.

What is 1 mpg worth to an HGV?

It depends on the mpg you start from, the miles you cover and the price of diesel. The gain from each extra mile per gallon gets smaller as the truck gets more efficient, because you are cutting a smaller number of gallons. Here is the method, so you can use your own figures:

1. Gallons used = miles divided by mpg.
2. Gallons saved = miles x (1 / old mpg - 1 / new mpg).
3. Litres saved = gallons saved x 4.54609.
4. Money saved = litres saved x the price per litre before VAT.

The price we use is the DESNZ weekly road fuel prices figure for the week of 26 October 2026: 199.22p a litre including 20% VAT. Dividing by 1.2 gives 166.02p before VAT. We use the price before VAT, which suits a fleet that reclaims it. If you do not reclaim the VAT, use 199.22p.

Which mpg figures should you start from?

Use your own telematics or fuel card figure if you have one. If you do not, the last published Department for Transport (DfT) figures give a starting point. They are old: the DfT has stopped publishing HGV fuel consumption, and 2016 was the last year. Its Transport Energy and Environment data tables page says the data “is not currently considered robust enough to meet our quality standards”.

For 2016, the DfT’s survey gave:

Vehicle	DfT 2016 survey, mpg
Artic, over 33 tonnes	7.9
Rigid, over 17 to 25 tonnes	9.5

We use these two as the starting points in the tables below. Treat them as indicative. Your own trucks may be better or worse.

What does the fuel cost per mile at those mpg figures?

At 166.02p a litre before VAT, fuel costs 95.5p a mile at 7.9 mpg and 79.4p a mile at 9.5 mpg. Pence per mile is the price per litre x 4.54609 divided by the mpg.

Starting mpg	Fuel cost per mile, ex VAT	Annual fuel cost at 60,000 miles	at 80,000 miles	at 100,000 miles
7.9	95.5p	£57,321	£76,428	£95,535
9.5	79.4p	£47,667	£63,556	£79,445

What is an extra 0.5 mpg or 1 mpg worth at 7.9 mpg?

At 7.9 mpg, an extra 0.5 mpg saves 6.0% of the fuel and an extra 1 mpg saves 11.2%. Here it is in litres and pounds a year, for one truck.

Annual miles	+0.5 mpg (7.9 to 8.4), litres	+0.5 mpg, £	+1 mpg (7.9 to 8.9), litres	+1 mpg, £
60,000	2,055	£3,412	3,879	£6,441
80,000	2,740	£4,549	5,173	£8,587
100,000	3,425	£5,687	6,466	£10,734

Multiply the figure by the number of trucks. For ten artics each doing 80,000 miles at 7.9 mpg, 0.5 mpg is worth £45,490 a year.

What is an extra 0.5 mpg or 1 mpg worth at 9.5 mpg?

At 9.5 mpg, an extra 0.5 mpg saves 5.0% of the fuel and an extra 1 mpg saves 9.5%. The saving is smaller than at 7.9 mpg because the truck already uses fewer gallons.

Annual miles	+0.5 mpg (9.5 to 10.0), litres	+0.5 mpg, £	+1 mpg (9.5 to 10.5), litres	+1 mpg, £
60,000	1,436	£2,383	2,734	£4,540
80,000	1,914	£3,178	3,646	£6,053
100,000	2,393	£3,972	4,557	£7,566

If you do not reclaim VAT, multiply each pound figure by 1.2.

How does diesel price change the answer?

Every figure above scales with the price per litre. The price in the DESNZ series hit 200.04p in the week of 12 October 2026, the highest since the series started in 2003. The tables use 166.02p because that is the ex VAT price for the latest week. If the price falls, the saving falls with it. If it rises, the saving rises. See UK diesel price history for how far it has moved in either direction, and our UK fuel prices page for the current week.

Can speed help an HGV save fuel?

Steady speed and holding the limit are the speed levers for an HGV. We do not put a per-mile saving on a lower speed for HGVs, and here is why. Goods vehicles over 3.5 tonnes must be limited to 90 km/h, about 56 mph, under regulation 36B of the Road Vehicles (Construction and Use) Regulations 1986. The Department for Transport’s fuel consumption curves for HGVs stop at 52 mph, which is below that limit. They cannot tell you what a lower motorway speed is worth to a truck.

What you can do is use the tables. Work out what 0.5 mpg is worth for your own mileage, then ask how much of that gap comes from the truck running at a steady speed at the limit, instead of surging and braking or running over the limit when the limiter is not working. A working limiter stops any driver running above the legal maximum. That protects your average mpg from the worst of the drift. It does not by itself raise it.

For the rest of the cost picture, see HGV MOT cost and operator licence cost. Fuel at these mileages dwarfs both.

Frequently Asked Questions

How much is 1 mpg worth to an HGV?

At 7.9 mpg and 166.02p a litre ex VAT, an extra 1 mpg is worth £6,441 a year at 60,000 miles, £8,587 at 80,000 miles and £10,734 at 100,000 miles. At 9.5 mpg it is £4,540, £6,053 and £7,566.

How much is 0.5 mpg worth to an HGV?

At 7.9 mpg, an extra 0.5 mpg is worth £3,412 at 60,000 miles, £4,549 at 80,000 and £5,687 at 100,000. At 9.5 mpg it is £2,383, £3,178 and £3,972. All use the diesel price for the week of 26 October 2026, ex VAT.

What is the average mpg of an HGV?

The Department for Transport’s last published survey figures, for 2016, were 7.9 mpg for artics over 33 tonnes and 9.5 mpg for rigids over 17 to 25 tonnes. The DfT has since discontinued the series, so use your own telematics or fuel card figures where you can.

How do I work out my own HGV fuel savings?

Multiply your annual miles by the difference between 1 divided by your old mpg and 1 divided by your new mpg. That gives gallons saved. Multiply by 4.54609 for litres, then by your price per litre.

Does a speed limiter improve HGV fuel economy?

Goods vehicles over 3.5 tonnes must be limited to 90 km/h by law. A working limiter stops any driver running above that maximum, which protects your average mpg. The DfT’s HGV fuel curves stop at 52 mph, so we do not quote a per-mile saving for HGVs from a lower speed.

Cut your fleet’s fuel bill

Put your own trucks, mileage and price into the HGV running costs tool to see your cost per mile and what a gain of 0.5 mpg would be worth to you.

On speed, the Department for Transport’s fuel consumption curves show a diesel van using 14.5% less fuel per mile at 60 mph than at 68 mph. For HGVs the law sets the cap at 90 km/h, so the gain comes from holding that limit. See HGV speed limiter law. How much reaches your bill depends on how many of your miles are driven above the cap.

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