More than one in three vehicles has failed to meet its fuel consumption promises in the latest round of real-world testing, and some cars have exceeded Australia's pollution limits.
The Australian Automobile Association published findings from its third round of tests on Wednesday, revealing eight out of the 21 vehicles tested overshot their advertised fuel consumption by more than five per cent.
In a shock result, one popular small car consumed 31 per cent more petrol than its manufacturer indicated.
The results come weeks after the federal government passed a fuel-efficiency standard in Australia, and before noxious emissions limits come into effect, which some of the vehicles tested would fail to meet.
The AAA tested a range of vehicles in the latest round of its $14 million program, including passenger cars, SUVs and utes.
The program, which is funded by the federal government, assesses the fuel consumption and emissions of vehicles as they drive on urban streets, rural roads and motorways, in tests based on European Union guidelines.
Of the 21 vehicles tested, eight used between six and 31 per cent more petrol than promised, with the 2023 Suzuki Swift using 31 per cent more fuel than indicated in its manufacturer's lab tests.
Other vehicles to exceed their advertised fuel consumption included the Mazda CX-5 (15 per cent), Skoda Kamiq (14 per cent), Mazda CX-3 (11 per cent), and Subaru Forester Hybrid (10 per cent).
AAA managing director Michael Bradley said the results showed motorists should research their vehicle purchases carefully as they could save money and environmental impact by making an informed choice.
"These tests show that when comparing vehicles, consumers and fleet (owners) cannot assume that vehicle performance as assessed by mandatory lab tests will translate into real-world savings or emissions reduction," Mr Bradley said.
"One 1.2-litre vehicle had similar on-road fuel consumption to several two-litre cars, and a hybrid SUV had a higher petrol consumption than a similar-sized conventional SUV."
The AAA tests also identified three vehicles that exceeded Australian laboratory limits for harmful nitrogen oxide - the Hyundai Venue SUV, and Mazda BT-50 and Toyota HiLux diesel utes - while the Suzuki Swift was found to produce double the lab limit for carbon dioxide.
The association also found three SUVs failed to meet particle emission limits that will come into effect in December 2025, with the Hyundai Venue, Subaru Forester Hybrid, and Volkswagen Tiguan falling short of the future standard.
The change, equivalent to Europe's Euro 6d fuel standard, will limit noxious emissions from light vehicles under Australian Design Rules.
The limit will come in addition to restrictions on vehicle emissions introduced by the New Vehicle Efficiency Standard recently passed into law and expected to be in place by January 2025.
