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Lexus IS 300h Review

The Lexus IS 300h has a 2.5-litre petrol engine, mated to a rear-wheel drive chassis, yet it emits just 99g/km CO2 – surely it’s a company car driver’s dream?

Green Car Guide Rating: 8/10

Key stats

  • Model/Engine size: IS 300h SE
  • Fuel: Petrol-electric hybrid
  • Fuel economy combined: 65.7mpg


  • The best driving 99g/km CO2 car on sale
  • Refined, smooth, quiet, comfortable
  • No instant reactions thanks to CVT transmission
  • Styling may not be to everyone’s tastes


This is now the third-generation of the Lexus IS, yet it’s the first one to be offered with a hybrid powertrain, and no diesel option; and the styling over three generations has evolved from conventional to angular – so is this what potential buyers want?

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Design & Engineering

The links between Toyota and Lexus are well known, so it may well be assumed that the IS hybrid shares the same engine and front-wheel drive powertrain base with the Prius. However this is not so – the IS 300h has a 2.5-litre, 4-cylinder petrol engine, producing 178bhp, and is rear-wheel drive. It also has a 141bhp electric motor powered by a nickel metal-hydride battery, using energy captured from braking. The engine and electric motor combine to provide a system output of 220bhp.

The IS has comfortable seats, a steering wheel with a sporty feel, and a cockpit that wraps around the driver, albeit with lots of straight lines. The interior image is one of high quality, as you would expect from a Lexus. The dials are digital, and the left dials changes from displaying whether the car is in a state of ‘charge’, ‘eco’ or ‘power’, to a more conventional, and useful, rev counter when in Sport mode. To change the temperature, you just slide your finger up or down the controller. This is certainly different, although it’s debatable whether this is more effective than a traditional dial.

In terms of exterior deign, the latest version of the IS has a fairly aggressive, busy, angular front end. At the rear, there’s a line that sweeps up from the sill under the rear door, along the bumper line from the rear wheel arch to the top of the rear light. Some people who are not as diplomatic as ourselves have commented that it looks like the IS has been hit up the rear by another car… It’s certainly a long way from the Lexus styling strategy when the first IS appeared, which was understated and conservative – an approach that was thought to be appropriate for premium cars. If we’re honest, we’re not sure that the new styling works as well as, for example, a BMW 3 Series.

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Lexus IS 300h Driving Experience

The Lexus IS 300h is an extremely refined, quiet, comfortable and generally pleasant place to be. At low speeds the car can run just on electric power for short distances. The petrol engine and hybrid drivetrain combination is powerful and smooth. There is no better driving experience in the sub-100g/km CO2 class from a non-plug-in car.

However the IS 300h has the normal Lexus/Toyota hybrid issue – the CVT transmission. The Toyota engineers say that this is the most efficient transmission for this hybrid system, but when you accelerate, the CVT takes a while to catch up, resulting in high revs, lots of noise, but no instant reactions in terms of quicker forward progress.

You may think that this problem has been solved in the IS 300h when you see that the gearbox has a manual mode, and there are even paddles on the steering wheel. Select Sport mode, together with the ability to change gear manually, and you can flick through the gears with the paddles, along with an accompanying throaty sound track. However both the manual gear selection, and the noise, is simulated. It can sound fun, but being a CVT, it has no physical effect on the gears. If the noise gets tedious, then you can reach down to a switch on the right of the dash below the steering wheel and turn down, or switch off, the ‘Active Sound Control’ (or noise synthesiser).

The IS infotainment system has a ‘mouse’ rather than a more conventional rotary controller as you’re likely to find in a BMW. If you think that this sounds more difficult to use on the go than a rotary switch then you’d be correct.

It’s also easy to be fooled by the satnav. At first sight, when you go to enter a destination, it looks like you can’t enter a postcode. However if you click on a small arrow at the top of the screen you get taken to a second page, where a separate option is provided to enter a UK postcode. This postcode option looks like a bit of an afterthought.

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Lexus IS 300h Economy and Emissions

The Lexus IS 300h has an official urban fuel economy figure of 64.2mpg, and also an extra-urban fuel economy figure of 64.2mpg. You would therefore imagine that the combined fuel economy would be a combination of 64.2mpg and 64.2mpg, in other words…64.2mpg. But no, the official combined fuel economy figure is… 65.7mpg. No we can’t work that out either. However the key thing is that the official emissions are just 99g/km CO2, which translates to a company car Benefit in Kind tax rate of just 11 per cent – which is amazing for a car that drives as well as the IS 300h.

Of course we know that virtually all cars have much worse economy in real-life driving, and hybrids are particularly difficult to achieve their official economy figures in real-life, unless you have a very light right foot. Our average real-life economy over a week with the IS 300h was 45.2mpg. With very careful driving we managed 60.5mpg, so it shows that it can be done, but it’s just extremely difficult to constantly drive so slowly on today’s roads without summoning the wrath of other motorists who aren’t likely to have the luxury of spare time on their side.

Note that in order to achieve 99g/km CO2 – and 65.7mpg – you have to go for SE-spec with 16-inch wheels (as on our test car).

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Price, Equipment and Model Range

The Lexus IS 300h SE costs £29,495. Our test car had the options of metallic paint (£610), Lexus premium navigation (£1,995) and parking sensors (£600), bringing the car’s total cost to £32,700.

SE is the entry-level spec – which comes with the smaller 16-inch alloy wheels. There’s also Luxury, F Sport and Premier spec. Luxury trim has emissions of 103g/km CO2, and 64.2mpg; Premier and F Sport have emissions of 109g/km CO2, and 60.1mpg.

The IS 250 is also available, with a 2.5-litre V6 petrol engine – and a poor 32.8mpg.

Most buyers in this class go for a diesel, but there’s no diesel in the IS line-up – Lexus would argue why should there be, as the hybrid has lower official emissions than a diesel – although real-life economy of the hybrid isn’t likely to be as good as a diesel, especially when spending lots of time on motorways – where this class of car will typically spend much of its life.


The Lexus IS 300h offers the best driving experience currently on offer for a sub-100g/km CO2 non-plug-in car. It’s refined, smooth, quiet and comfortable. The 2.5-litre engine, combined with the electric motor, has the potential to provide sports car levels of dynamics, but this never quite happens thanks to the CVT transmission, which dulls the car’s responses. The interior is a pleasant place to be, but the angular exterior seems to have moved far away from the understated, classy styling of early Lexus models.

However it’s the 99g/km CO2 emissions that are the big selling point of this car, resulting in a very attractive company car Benefit in Kind tax rate of just 11 per cent. This translates to an official combined economy figure of 65.7mpg, although you have to drive extremely carefully to get anywhere near that mark. So overall the Lexus IS 300h is a compelling proposition for company car drivers, and a pleasant driving experience for private buyers. It is awarded a Green-Car-Guide rating of 8 out of 10.

Car facts and figures Lexus IS 300h Review

  • Fuel economy extra urban: 64.2mpg
  • Fuel economy urban: 64.2mpg
  • Test economy: 45.2 mpg
  • CO2 emissions: 99 g/km
  • Green rating: VED band CA – First year £0
  • Weight: tbc Kg
  • Company car tax liability (2012/13): 11%
  • Price: £29,495
  • Insurance group: 32A
  • Power: 220 bhp
  • Max speed: 125 mph
  • 0-62mph: 8.3 seconds
Paul Clarke

Review by:
Paul Clarke, GreenCarGuide Editor