UK study finds hybrids fall way short of economy ratings

Some plug-in hybrids missed their advertised ratings by almost 6 L/100 km

Published: June 6, 2018, 2:30 AM
Updated: June 9, 2018, 5:06 AM

2015 Toyota Prius Plug-In

You remember dieselgate? Well, get ready for hybridgate: a recent study out of the UK has found that just about every hybrid car on sale can’t match its advertised fuel economy ratings.

2016 Toyota Prius

The study was conducted by, the consumer motoring site that advocates transparency in real world motoring issues. It analyzed 148,000 real fuel economy reports submitted by drivers and found that only one in 39 hybrids (self-charging or plug-in) delivered on its advertised fuel ratings.

That’s not a very good record, but even more alarming is that some (mostly plug-in models) missed their advertised ratings by as much as 5.9 litres per 100 km. That means that if you bought a PHEV hoping to spend say $5 for every 100 km you drive, you might actually spend closer to $13, at today’s prices.

2018 Mitsubishi Outlander PHEV badge

“While these models are advertised with lofty (fuel economy) figures that will appeal to cost conscious drivers, our research shows that on-the-road economy is somewhat different,” said Honest John’s Managing Editor, Daniel Powell. “Given that car buyers are being urged to replace their (gasoline) and diesel cars with new low emission hybrids, we think more needs to be done to ensure drivers get a fair deal when it comes to (real-world economy).”

Among the worst, the Mitsubishi Outlander PHEV (which placed 4th on Honest John’s list, achieving just 42.5% of its claimed economy), the Toyota Prius Hybrid (achieving 62% of its target), Lexus RX 450h (63%) and Lexus NX 300h (68%).

Mitsubishi Outlander PHEV

All those models fell short of the average score, which Honest John pegged at 70% of the advertised economy. The best hybrids to match their advertised figures are the Lexus GS 450h (which achieved 84.2% of what it advertised), Toyota Rav4 Hybrid (79.3%) and Kia Niro (77.4%).

Honest John attributes the discrepancies to laboratory testing, saying that manufacturers have been fined for exceeding their average CO2 emissions in accordance with their economy and emissions laboratory results. To avoid fines, manufacturers have optimized their vehicles for the lab, rather than real world roads.

2018 Kia Niro

Europe recently replaced its old European Driving Cycle test (NDEC) for the Worldwide Harmonised Light Vehicles Test Procedure (WLTP), which is more reflective of real-world driving with longer distances and higher speeds. However, it will not apply until September 2018, so it will be interesting to see what the discrepancies will be in 2019 model year hybrids.