Lexus IS 300h MPG & CO2 emissions

The Lexus IS 300h looks clean compared to diesels, but plug-in rivals are better still

Lexus IS 300h
MPG (combined) MPG (high) MPG (low) CO2 emissions
44-49mpg 53mpg 44mpg 104-109g/km

When compared to more traditional choices, there’s no doubt the Lexus IS 300h offers an appealing option for emissions-minded motorists. It combines competitive CO2 output with appealing MPG figures, although real-world consumption will likely be a bit higher than claimed.

Lexus IS 300h MPG

Our own experience with the Lexus IS 300h is that you’ll struggle to achieve the officially quoted consumption of just under 50mpg. When our sister title Auto Express had one on the fleet, it recorded an average of 41mpg – that’s a little worse than the sort of real-world consumption you might expect from a comparable diesel, but a long way off the quoted figure.

CO2 emissions

Lexus has recorded official CO2 tailpipe emissions figures of 104-109g/km for the IS 300h. While that’s good in comparison to the numbers quoted for traditional diesel or petrol executive models, it’s hardly noteworthy if you’re looking at the latest batch of plug-in hybrids. They can take advantage of much bigger batteries to drive relatively long distances in electric-only mode, and as a result score better in the emissions tables.

In fact, the IS 300h sits much closer to traditional diesel cars like the Mercedes C 220 d, with its 121g/km CO2 output, than it does to PHEVs. The overall value of the hybrid system depends on the type of mileage you cover, and your driving style. Use a Lexus IS 300h a lot around town, and you’ll get maximum benefit from its electric motor. If you do a lot of B-road mileage, or want to make the most of the power and grip, the numbers will inevitably suffer.