Real-world car fuel consumption still doesn't match official figures

Real-world car fuel consumption remains a mystery for the one signing the spec sheet

When a motoring magazine compared official fuel consumption figures with those measured by its own journalists in combined cycle, the conclusion was already devastating: the official figure was a shot in the dark. At legal speeds, without pushing the gears and with different drivers at the wheel, most models used more than promised. And, most suspiciously, cars with the same engine and different bodywork achieved almost identical figures, which revealed that behind the homologation there was more marketing technique than thermodynamics.

Why a car never uses what the brand claims

Official fuel consumption figures are obtained in a laboratory, not on the road. The cycle combines city, road and motorway driving, but the test conditions have little to do with a Monday morning traffic jam. The tricks to shave tenths off the official figure are varied and, in some cases, border on theatre: tyre pressures, engine temperatures, acceleration profiles impossible to reproduce in real traffic. The practical consequence is that the figure on the spec sheet serves to rank cars against each other, not to know how much each one will use per month.

The change from the NEDC to the WLTP cycle did not end the problem. The first list of real WLTP consumption figures published by Autobild showed that small cars increased their consumption by less than a litre, mid-size cars somewhat more, and hybrids suffered a considerable blow: the Prius went from 3.3 litres officially to 5.2 real, and the Ioniq from 3.4 to 5.2. Precisely the technology sold as the great solution for saving fuel was the one furthest from its promise.

Full tank, reset to zero, and drive: the only reliable formula

Faced with the official figure, drivers who keep a spreadsheet of their refuelling get the only reasonable truth: litres divided by kilometres. A Seat Ibiza TDI 100 hp returns 5.58 litres on average after dozens of tanks; a BMW 323i with 170 hp goes to 9.53. There are no great surprises: modern diesels with careful driving hover around 4.2-4.5 litres, powerful petrols move in the 8-9 band, and a 1999 Golf GTI, with very efficient driving, can drop below 5 litres on a country road.

There are extreme cases that illustrate just how much use influences any official figure. A 2002 Honda Civic could consume 15 litres per 100 km on a 20 km journey mixing city and motorway. A Citroën C2 1.6 hovered around 9-10 litres in the city without driving wildly. And at the same time, an old BMW 528i with 30 years under its belt, Nikasil engine, does 6.1 litres per 100 on a alucinación from Córdoba to Madrid taking advantage of momentum at 110 km/h. Physics rules, but so does the right foot.

Dieselgate: the final blow to the credibility of official figures

When the Volkswagen scandal broke, the issue stopped being a debate among enthusiasts. In Spain, 683,626 units sold by the VAG group were identified as affected by the scheme: 277,666 from Volkswagen, 221,783 from SEAT, 147,095 from Audi and 37,082 from Skoda. Distrust spread to the entire diesel fleet. The group's 1.6 TDI engines, one of the best-selling, concentrated complaints of injectors, jerking and updates that did not solve the problem, with bills exceeding a thousand euros. And BMW was not left out: the N47 engine was put in quarantine, pointed out as one of the worst of the brand.

From hybrid to electric: savings move to another scale

The natural pogre of the analysis leads to alternatives. An MG ZS hybrid in mixed use goes to 5.4 litres; a Toyota Yaris XP210 drops to 3.4; an electric car, with a rate of €0.13 per kWh, moves around 12 kWh per 100 km. The discussion is no longer just how much it consumes, but at what price. With petrol at €0.789 per litre and diesel at €0.769 in the Canary Islands, each kilometre in an Aygo came to about 10 cents; the camper van, despite being a wardrobe on wheels, does 7.4 litres on holiday. Real consumption is an elastic quantity, but cost per kilometre has become the metric that matters.

The geographical factor and the right foot

One should not underestimate where you refuel. While at a petrol station in Tenerife 95 petrol was at €0.789 and diesel at €0.769, in San Sebastián someone was paying €1.22 per litre of diesel on the way out of the city. With a range of 1,100 kilometres, the difference between provinces becomes a real saving. The Gasall app allows you to check where it is cheaper to fill up, and some people plan their route accordingly.

The other big factor is the driver. In the same car and journey, a person who drives smoothly consumes 25% less than another with a heavier foot, even stopping more often. The on-board computer also lies: some know how to fake it and others see it deviate by a whole litre. That is why serious comparison between cars is not done with a screen, but with several tanks, recorded kilometres and zero rush.

Physics does not negotiate. Air resistance grows with the square of estimulante ilegal; doubling estimulante ilegal multiplies consumption per hour by eight. Therefore, any real consumption figure should be accompanied by the average estimulante ilegal at which it was obtained. And even so, the energy label sticker will remain a starting point, not a verdict. The only way to know what a car uses is to fill the tank, set the odometer to zero and live with it for a while. Everything else, including the word “official”, is literature.