Lexus turbocharges IS sedan

Lexus Australia has announced that the IS 250's 2.5-litre V6 will be replaced by a newer 2.0-litre turbo-petrol four-cylinder engine in September.

Despite being half a litre smaller and offering two fewer cylinders, the newly named IS 200t entry model will produce significantly more performance.

Matched with an eight-speed automatic transmission like the IS 350, the IS 200t produces 180kW of power and 350Nm of torque – the same as the 2.0-litre turbo-four in BMW's 328i sedan.

That's a sizeable 28kW and 98Nm more than the 153kW/252Nm offered by the outgoing IS 250 V6, which comes with a six-speed auto.

The rest, says Lexus, is 0-100km/h acceleration in seven seconds – more than a second sooner than the IS 250 (8.1 seconds) but eight-tenths slower than the 328i (6.2).

Lexus also claims the new engine – first seen here in the 175/350Nm Lexus NX 200t – offers maximum torque over a wide 1650-4400rpm (peak power comes at 5800rpm) and delivers “superior smoothness and responsiveness, with no turbo-lag and high fuel efficiency".

Producing 53kW and just 28Nm less than the IS 350's 233kW/378Nm 3.5-litre V6, which consumes 9.8L/100km, the same engine will also power the fourth-generation RX 200t, which similarly replaces the existing entry-level RX 270 next year.

Fuel consumption figures have not been announced, but in Europe Lexus is claiming 7.0L/100km for most models or 7.2L/100km for models riding on 18-inch wheels.

That makes the IS 200t less efficient than the BMW 328i, which consumes 6.3L/100km even on 19-inch wheels.

The Toyota group's first turbocharged four-cylinder petrol engine features VVT-iW (Variable Valve Timing intelligent — Wide), which allows it switch between the Otto and Atkinson cycles, plus D-4ST fuel-injection, a water-cooled cylinder-head with integrated exhaust manifold and twin-scroll turbo.

Meantime, Lexus says the IS 200t's paddle shift-operated Sport Direct Shift gearbox, which was first developed for the RC F coupe, makes it the is the first Lexus sedan to vary gear shifts according to g-forces.

In theory, it automatically downshifts during hard braking into a corner, holds a lower gear through the turn and then selects the most appropriate gear to exit the corner for optimum throttle response.

Lexus Australia chief executive Sean Hanley said the IS was an ideal platform for the new powerplant.

"This very advanced engine has already proven itself and been valued by Lexus customers in the NX 200t," Hanley said.

"It will also be extremely well matched to the IS 200t, delivering excellent performance and fuel efficiency to complement the driving pleasure already offered by the IS."