LONDON, England - British car-buyers' guide WhatCar? has conducted a survey on fuel consumption and found new-car buyers will pay an average of £1000, equivalent to R17 740, over three years.VIDEO: What Car? True fuel-consumption dataThat's how much more buyers who trust UK government-sanctioned fuel-consumption data will spend than they expected given claimed data. Official figures are achieved under laboratory conditions that can rarely be replicated in the real world.What Car?'s True MPG data is scientifically calculated by experienced engineers who drive test vehicles on a variety of real roads, including motorways, secondary and minor roads and through towns and villages.ONLY RELIABLE FIGURESSince launching True MPG two years earlier What Car? has tested about 400 cars in real-world conditions using cutting-edge test equipment to achieve consumption figures on average 19% worse than the government figures.What Car? editor Jim Holder said: “What Car?’s True MPG tests are the only reliable source of real-world fuel economy. With such a discrepancy between the official figures and our real-world data it’s clear that the official test processes need to be updated so that car buyers can place more trust in the figures they are being told."Meanwhile, car dealers and the car industry aren’t obliged to advise consumers about fuel consumption beyond pointing at official statistics.”In a mystery-shopper exercise that visited 100 dealers of eight major car brands, What Car? found that many sales staff either stuck rigidly to official data or avoided answering questions on fuel economy/efficiency/consumption altogether.Brand realistic mpg advice provided: • Audi 0% • Toyota 25% • Volkswagen 25% • Nissan 25% • Peugeot 38% • Renault 38% • Ford 50% • Dacia 63%Below is What Car? fuel consumption compared to official figures released:Dealers are entitled to do this but this stance means that customers will have little idea that they could be nearly R18 000 worse off than they expected on purchase after owning their car for three years.1.8-million people have used the What Car? True MPG online tool to calculate their car’s real-world consumption.What Car? tests the vehicles using a portable emissions-measurement system when engines have reached normal operating temperature. The test equipment considers driving style, changes in altitude, ambient temperature and humidity and engine temperature.The tool allows buyers to select a car personalised to their driving needs and budget and to accurately predict the fuel consumption they can expect.The principal component of the testing equipment is a gas analyser which measures carbon dioxide output (from which the grams/km figure is derived). The equipment simultaneously captures carbon monoxide, nitrous oxide, nitrogen dioxide and, optionally, total hydrocarbons.From the carbon dioxide output and knowledge of the exact fuel in the tank, the fuel consumption in km/litre can be calculated via the mass balance method with a high degree of accuracy.Throughout each test, the output of each gas is captured at one-second intervals, together with the engine performance readings from the engine control unit via the CAN bus a communication device. Further, a high-grade GPS unit and weather probe capture these readings at the same frequency.