FUEL ROUTE TESTING
My question relates to fuel consumption. I read the 2012 and 2013 CAR articles on the standardised EU test figures and I understand it. I am spe‐ cifically looking for details of CAR’S fuel route. What if there is a massive headwind on the day of your test? Do you test on the same day and time of the week? Do you make use of the Eco function (if available) when conducting fuel route testing? I started looking at different first car options and fuel consump‐ tion in the real world is im‐ portant to me.
JOHAN HAARHOFF
Port Elizabeth
You mentioned that you under‐ stand the EU test figures and how they are generated in a test facility on a dynamometer under con‐ trolled conditions driving a set drive cycle. The previous NEDC test method has now been re‐ placed with the WLTP cycle to achieve more realistic results. Un‐ fortunately in South Africa we still use the NEDC figures and that is one of the reasons CAR decided to also conduct a fuel-route test to give the reader another fuel figure that is real-world derived.
It must be stated that this test is not scientific as there are too many variables that simply can‐ not be controlled. Even if you drive at the same time of day, traffic conditions and weather may not be the same. We try and control some variables on our 100 km road test that consists of city and motorway driving:
• Same driver for all fuel route testing (when possible)
• Aircon always on (to cater for winter and summer tests)
• Adhere to speed limits and keep with the flow of traffic. No harsh accelerations or braking
• Test in default drive mode not in Eco or Sport modes
• Use the onboard computer’s reading as this is more accurate over 100 km than a tank-to-tank test topping up with so little fuel
The fuel-route figure should only be seen as extra information and not a definitive figure. Remember that even though the official, NEDC fuel consumption figures are unrealistic, they are still com‐ parable. A vehicle with a better NEDC figure would also consume less fuel on the road in most cases.
Always remember that the biggest influence of fuel economy is driving style (and drive cycle). You can have the most fuel-effi‐ cient car but if you have a lead foot then all will be to no avail. Buying your first car is a special event and we trust that with all the knowledge you gained by reading CAR will result in the per‐ fect vehicle in your driveway!