The 2013 Lexus IS has launched in Australia this week, featuring a new petrol-electric variant called the IS300h.
It replaces the IS220d diesel model that was previously sold in Europe but not Australia.
Lexus’s chief engineer for the new IS said at the car’s Australian launch that the company had weighed up whether to take the hybrid or diesel route to improved carbon dioxide (CO2) emissions.
“In the beginning of [developing] this product, especially for Europe, the CO2 regulations become severe and severe… so we carefully investigated which direction – diesel or hybrid – had potential for the future. Not so right now but in the future,” Junichi Furuyama told CarAdvice.
“Yes, yes [in about 10 to 20 years]. Of course we can engineer a new diesel engine. But we don’t have suitable unit so [we would] have to build new one. We investigated many cases, but conclusion was that hybrid was solution to future severe regulations.
“In case of diesel, some kind of devices were needed to reduce not the CO2 but HC [hydrocarbons that along with nitrogen oxide (NOx) in diesel fuel contribute to greenhouse gases and smog] for Euro 6 or Euro 7.”
The new Lexus IS hybrid squeezes under the magic 100g/km CO2 barrier in the UK, with its 99g/km figure helping Britons save hundreds of pounds in company car tax.
Differing specifications – including larger wheels – mean the IS300h sold in Australia has a slightly higher figure of 113g/km, with fuel consumption of 4.9L/100km.
The Audi A4 and BMW 3 Series both have diesel models that boast even better efficiency, though Lexus Australia says the IS300h will have the higher star rating according to the government’s Green Vehicle Guide ratings.
The IS hybrid is significantly more economical than the alternative petrols – 2.5-litre and 3.5-litre V6 engines that carry over from the old model. The IS250 has official consumption of 9.2L/100km, with the IS350 rated at 9.7L/100km.
Furuyama-san acknowledges that many diesel buyers, including in Australia, are tapping into the driveability benefits brought by the high-torque engines.
He says while the hybrid can’t match the torque outputs of the German diesel engines that it offers other benefits.
“Yes, it’s kind of challenge for us [to achieve great driveability],” he said. “Especially in Europe, they love diesel – much torque and acceleration performance.
“At the beginning planning of this car we set two targets – one is [matching] competitor diesel engines in terms of CO2, and second target is power, performance – the intermediate [in-gear] acceleration, not 0-100.
“Max performance if compared to diesels such as 320i … max torque is not so comparable but intermediate acceleration is very good because the pick up of the [electric] motor is very smooth, very quick when compared with a diesel engine.
“The issue is max performance if compared to diesels such as 320d – is little bit worse than competitors’ engines, and in Europe there are many criticisms for this IS300h for max power and torque. Diesel has more punch in drive feeling.
“So it is a compromise between consumption/emissions and performance. So we carefully watch the reaction in Europe and also Australia to the hybrid to see if we can compete with diesel competitors or not.”
Lexus continues to develop a new four-cylinder turbocharged petrol engine.
It’s set to make its debut in a new compact Lexus SUV due to debut later in 2013. The downsized engine is expected to eventually replace the 2.5-litre V6 in the IS, though it’s unlikely to happen until the new generation’s mid-life facelift in a few years’ time.