Why does your hatchback, sedan or SUV give you a mileage different from what the car manufacturer claims under test conditions?This question made a Mizoram University professor and a research scholar invent a measuring device that yields a near-accurate mileage of a car per litre of fuel. Theirs is one of 25 patents applied for by teachers and research scholars of the university at Tanhril, about 15 km from State capital Aizawl.“Accurate knowledge of automobile mileage is crucial as it is an important performance index parameter of a vehicle during on-road operation. But the mileage achieved by a vehicle during actual road transport applications generally deviates from the manufacturer specifications under controlled conditions for a few driving cycles,” Hranghmingthanga, a professor in Mizoram University’s Department of Physics, told The Hindu.He and research scholar L. Lalnunthari worked on a mechanism that, unlike laboratory measurement, took into account factors such as road condition, driving style, traffic congestion, fuel quality used, gradients, and load on the vehicle.The inexpensive device entailing a digital multimeter, a pipe, and a calibrated fuel container was tested on an 800 cc petrol hatchback under conditions experienced by drivers on the road. “The margin of error in measuring the accurate mileage in kilometres per litre was 10%,” said Mr. Hranghmingthanga said.The device can be used for measurement when the car is stationary. “We can do the reading before starting the engine and after the ignition is switched off at the end of a trip,” said Ms. Lalnunthari.The duo declined to get into the details of their invention expected to be elaborated upon in a science journal soon. “It would suffice to say that it is intended to help vehicle manufacturers give the true average mileage and possibly work on more fuel-efficient engines,” said Mr. Hranghmingthanga.“Our university has had a tremendous year with applications filed for 25 patents by various departments. We have also attracted projects worth more than ₹40 lakh, and our aim is to be a topper among higher education institutes in the country,” said Mizoram University Vice-Chancellor K.R.S. Sambasiva Rao said.