A post on the UK Kia Owners Club today by member wiffysmell96 attracted my interest. It reads as follows :-
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If your Kia has a dashboard display that shows average mpg here is a test you can do to see if it will ever get near the official extra urban figure. I put the test first and the explanation afterwards. The official test lasts for 400 seconds and has an average speed of 39 mph/62.6kmh. You need a warm engine and a flat road, the A14 past Newmarket is very good for this, and preferably a sat nav for speed reference. If you have cruise control all the better.
For a 5 speed gearbox.
The test; accelerate to 50 mph in 5th gear, lift off and reset the average mpg figure. When the car reaches 39/40 mph slowly depress the accelerator until the engine just picks ups (it is important that the accelerator catches up with the car rather than the other way round) then feather the accelerator (be gentle) to maintain 39 mph and keep this up for 6 miles and take the reading from the average mpg. If the car struggles change down to fourth gear and start the test again in fourth. If you have cruise control hit the set button at 39 mph. ideally you should do 3 tests in 5th gear and three tests in 4th gear, if you have cruise control three of each with manual speed control and three of each with cruise control. Use the best figure achieved as representative.
Subject to lots of caveats: Tyre pressure OK, no roof box/rack, minimum fuel in tank, driver only, car maintained. If the official test was conducted at or about sea level and at or about 20C and you are at or about see level, then:
If the temperature is 20C or above you should at least equal the official figure if the test is below 20C but above 0C you should be no less than 7.5% worse than the official figure. If the official test was conducted at or about sea level but at the lowest air density allowed, then if you are at or about sea level and the ambient temperature is above 0C then you should be no worse that 15% below the official figure.
Because the above test involves constant speed/load it should provide a better result in the same conditions as the official test and is how fuel consumption tests were conducted before the eu test came into being. The eu test is meant to be more representative of real world driving. Acceleration whether from standstill or from some lower speed uses more fuel than maintaining speed as does gear changing etc.
The official test includes acceleration, deceleration, idling, steady speed and gear changing in 13 phases as follows;
Idling 5,0%
Idling, vehicle moving, clutch engaged on one combination 5%
Gear-changing 1.5%
Accelerations 25.8%
Steady-speed periods 52.%2
Decelerations 10.5%
Because the test allows the air density to vary about the density at the reference temperature (20C) by +/-7.5% you get a range of possible results.
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What do our experts think about this?
