Tips to Improve MPG: What Works and What Does Not

If you want a straight answer on tips to improve mpg, start with the maths, not a guess. This page works through the formula step by step, runs a worked example with the assumptions stated in full, and gives you a table you can read your own numbers off. Everything here uses the same definitions throughout, so the figures in the table match the figures in the example.

The short version is that tips to improve mpg comes down to two measurements you can take yourself: how far you drove, and how much fuel you used. Get those two right and the rest is arithmetic. Get either one wrong — a half-full tank, a trip meter that was never reset, a gallon confused with a litre — and the answer is meaningless, however carefully you divide.

The formula — tips to improve mpg

MPG = miles driven ÷ gallons used. Everything else on this page is built on that one line. For the worked example below, the car covers 360 miles on 10.0 gallons, which gives 360 ÷ 10.0 = 36 MPG. In metric terms the same economy is 6.53 L/100km using a US gallon, or 7.85 L/100km using a UK imperial gallon — label which gallon you used, because the two figures differ by about 20 percent. The formula looks trivial, and it is, but the measurement behind it is where people go wrong: the miles must be the miles actually driven between the two fills, and the gallons must be the gallons actually pumped, not the size of the tank and not a dashboard estimate.

Worked example — tips to improve mpg

Suppose the car is used for a week of commuting plus a weekend trip. The trip meter reads 360 miles between fills, and the second fill takes 10.0 gallons. MPG = 360 ÷ 10.0 = 36 MPG. In metric terms that is 6.53 L/100km (US gallon) or 7.85 L/100km (UK imperial gallon). At an example fuel price of $3.85 per gallon, the fuel for that 360-mile stretch costs (360 ÷ 36) × $3.85 = $38.50, which is $0.11 per mile. That per-mile figure is the one worth remembering, because it turns any future journey into a cost: multiply the miles by $0.11 and you have the fuel bill for that trip at this example price. If your next tank gives a different MPG, do not be surprised — one tank is a sample, not a verdict. Log three or four tanks, add all the miles together, add all the gallons together, and divide the totals: that averaged figure is the one to trust.

MPG and fuel cost at a glance — tips to improve mpg

The first table converts common MPG figures to litres per 100 km in both gallon types. For tips to improve mpg, the same reasoning applies — measure brim-to-brim, average several tanks, and use your own figures rather than a quoted one. The second turns the example economy of 36 MPG into fuel costs at three example prices across three distances — replace the example price with the one you pay and the maths is identical.

MPG L/100km (US gallon) L/100km (UK imperial gallon)
20 11.76 14.12
25 9.41 11.30
30 7.84 9.42
35 6.72 8.07
40 5.88 7.06
45 5.23 6.28
50 4.70 5.65
Distance $3.45/gal $3.85/gal $4.25/gal
100 miles $9.58 $10.69 $11.81
250 miles $23.96 $26.74 $29.51
500 miles $47.92 $53.47 $59.03

What actually improves MPG — and what does not — tips to improve mpg

The biggest gains come from the cheapest changes: steady speed, gentle acceleration, looking ahead so you brake less, and keeping the car maintained. That is the point to carry into tips to improve mpg: the method is the same, but the numbers are yours, so the example here is only a starting point. Tyre pressures at the placard figure, a clean air filter, and removing a roof box or heavy load you no longer need all help, and they cost little or nothing. Driving slower on the motorway helps too, because aerodynamic drag rises steeply with speed — the difference between a steady cruise and constantly speeding up and slowing down is larger than most gadgets claim to deliver. What does not help is most of what is sold as a miracle: fuel additives, magnetic devices and similar products have no credible mechanism for improving economy, and any gain they appear to give is usually the driver paying more attention after fitting them. Measure before and after, brim-to-brim, and believe the measurement, not the packaging.

Common mistakes — tips to improve mpg

The most common mistake is mixing gallons: US and imperial gallons differ by about 20 percent, so a figure converted with the wrong gallon is wrong by the same margin. Read the figures on this page about tips to improve mpg as a worked illustration, and swap in your own miles, gallons and price to get your own answer. Next is trusting a single tank — one short fill or one unusual journey can tilt it badly — instead of averaging several. Third is reading the trip meter without resetting it at the fill, which mixes miles from before the fill into the calculation. Fourth is using the tank's capacity instead of the gallons actually pumped; the capacity is not the amount you used. And fifth is comparing a dashboard figure with a brim-to-brim figure as if they were the same measurement: the dashboard estimates from the engine's data, the brim-to-brim method measures what actually went in, and they disagree by a few percent in either direction.

Related calculations — tips to improve mpg

If this page answered your question, these pages take the next step — the same method applied to a closely related question, or the calculator that does the arithmetic for you. For tips to improve mpg, the same reasoning applies — measure brim-to-brim, average several tanks, and use your own figures rather than a quoted one.

Putting your tips to improve mpg figure to work

Putting the figure to work is where the method pays off. That is the point to carry into tips to improve mpg: the method is the same, but the numbers are yours, so the example here is only a starting point. Once you know your own MPG, measured brim-to-brim over several tanks, you can price any journey before you set off: multiply the miles by the fuel price divided by your MPG, and the answer is the fuel cost of that trip at that example price. You can also compare cars honestly, because you are comparing measured figures rather than brochure claims. Keep a simple log — date, miles, gallons, price — and review it monthly. Patterns show up quickly: a winter dip, a motorway improvement, a slow decline that points to tyre pressures or a change in routes. The log turns a vague feeling about fuel use into a number you can act on, and that is the whole point of measuring in the first place.

Frequently asked questions

What is a good MPG figure?

It depends on the car and how it is used. Read the figures on this page about tips to improve mpg as a worked illustration, and swap in your own miles, gallons and price to get your own answer. A small petrol car on mixed driving, a large SUV and a diesel on motorways all have different sensible ranges, so a single number cannot judge them all. The useful comparison is your car against itself: measure brim-to-brim over several tanks and see whether the averaged figure is stable on similar journeys.

How do I calculate MPG from litres?

Divide the litres by 3.785 to get US gallons or by 4.546 to get imperial gallons, then divide the miles driven by that gallon figure. That is the point to carry into tips to improve mpg: the method is the same, but the numbers are yours, so the example here is only a starting point. Say which gallon you used, because the two give MPG figures about 20 percent apart.

Why is my MPG lower than the dashboard says?

The dashboard estimates from engine data and recent driving, while the brim-to-brim method measures the fuel that actually went into the tank. Read the figures on this page about tips to improve mpg as a worked illustration, and swap in your own miles, gallons and price to get your own answer. They commonly disagree by a few percent in either direction. Trust the brim-to-brim average over several tanks for planning and expenses.

How many tanks should I average for a reliable MPG?

Three or four tanks is a good minimum. Read the figures on this page about tips to improve mpg as a worked illustration, and swap in your own miles, gallons and price to get your own answer. One tank is noisy — a pump clicking off early or one unusual journey can tilt it — while averaging the totals over several tanks smooths those effects out and gives a figure you can rely on.

Does driving slower always improve MPG?

Up to a point. That is the point to carry into tips to improve mpg: the method is the same, but the numbers are yours, so the example here is only a starting point. Very slow driving in low gears is inefficient, and very fast driving wastes fuel on aerodynamic drag. Most cars are at their most economical at a steady moderate cruise, with smooth acceleration and as little braking as possible. The exact sweet spot varies by car.