Real-world fuel consumption figures show huge differences in your MPG
Published 13/07/2016 | 02:30
It has largely gone unnoticed, but recent 'real-world' tests found cars are using up to 2.7-litres more fuel per 100kms than their manufacturers claim.
That emerged from new trials of 30 core models produced by the PSA Group. In all cases, cars used more fuel than 'official' figures - with gaps ranging from 1.2-litres/100km to 2.7-litres/100km.
That means fuel costs are much higher than motorists might expect when buying.
In the case of a diesel car, it could be an extra €3-plus every 100kms.
The decision to publish the realistic consumption results was taken by the PSA Group, which produces Peugeot, Citroen and DS cars. They did so as buyers of nearly all brands have lost faith in official data from near-perfect official test conditions.
However, these lower figures do play a large part in determining our Vehicle Registration Tax (VRT) and road tax.
Consumption effectively determines emission levels and, therefore, taxation categories.
So we are 'getting away' with lower tax - for now at least.
PSA sources say they believe their results are much better than many rivals would be under similar conditions - suggesting even wider gaps between real and official numbers for many brands.
The new data emerged from tests based on the EU's 'Real Driving Emissions' (RDE) project, which uses a portable measurement system in the vehicle.
Also involved were two non-governmental organisations - the Brussels-based Transport & Environment (T&E) and France Nature Environment (FNE).
The tests were overseen and audited by independent international body Bureau Veritas.
A mix of professional and amateur drivers not directly employed by the company was used.
The tests were carried out on all sorts of public roads (25km urban, 39km rural, 31km motorway) with typical passenger and luggage loads. Air conditioning was turned on, too.
That's in sharp contrast with the 'un-real' testing procedure for 'official figures', where cars are driven on smooth, level surfaces with low-rolling resistance tyres and no air con or luggage etc.
PSA decided last November to commit to publishing the real-world tests at a time of deep consumer cynicism about official results.
The three brands are now planning a simulator on their websites, so you can predict your car's consumption depending on inputs such as driving style and conditions.
And next year, they intend to measure levels of nitrogen oxide (NOx) in 'customer driving conditions'.
NOx emissions were at the centre of the Volkswagen scandal.
The EU has been planning to move to a new Worldwide Harmonized Light Vehicles Test Procedure (WLTP) in the near future.
It is expected to better align official and real-world fuel consumption values.
But, be warned, it could mean higher VRT and road tax.