That Kia India has two diesel compact SUVs on sale says a lot about the fierce competition in the 8 car-strong segment. The Syros and Sonet share the 1.5-litre diesel engine and the 6-speed automatic gearbox, but are rated differently by ARAI; the newer Kia compact SUV is rated at 17.65kpl, while the older Sonet has an ARAI mileage of 18.6kpl. We find out if the difference is the same in the real world with our exhaustive and accurate mileage tests.

Kia Syros vs Sonet diesel specifications and price

Syros is up to 95kg heavier than the Sonet

In terms of powertrain specifications, the Syros and Sonet diesels are identical, though the former is up to 95kg heavier than the latter, which could explain the 0.95kpl difference in their ARAI mileage figures. Prices for the Syros diesel are much higher than the Sonet, as the newer compact SUV targets a buyer looking for a more premium rear seat experience.

 Kia Syros vs Sonet diesel real world mileage

Sonet diesel-AT delivers 4.1kpl more than the Syros

When put through our city mileage tests, the Sonet diesel-automatic went 3km further on a litre od diesel than the Syros with the same engine and gearbox, while our highway test showed Kia's older compact SUV delivered 5.2kpl more. Overall, the Sonet's real world mileage is 4.1kpl higher than the Syros with the same powertrain, which means that the Sonet diesel-automatic can go a significant 185km further on the 45-litre fuel tank.

This also means that while the Sonet diesel-AT's real world mileage figure is about 2.3kpl less than the ARAI number, the Syros real world milage is 5.45kpl less than the quoted figure.

Autocar India’s fuel efficiency testing

Before our real-world fuel efficiency tests, we fill our test cars’ tanks to the brim and maintain tyre pressures based on the manufacturer’s recommendations. These cars are driven in fixed city and highway loops in and around Navi Mumbai, and we maintain certain average speeds. Throughout the tests, there is only one person in each car, running the aircon and other electricals, such as the audio system, indicators and wipers, when required, just like a regular user would. Periodic driver swaps further neutralise variations in driver patterns. At the end of each cycle, we calculate efficiency by filling the tanks to full again.