Nissan has revised the 1.5-litre diesel engine in the Juke, boosting its performance and efficiency but keeping the price the same.

An extra 15lb.ft of torque makes it even gutsier, and with 80% of the total 192lb.ft being available from 1,500rpm, the engine also has excellent driveability.

However, CO2 emissions have been reduced to 109g/km with corresponding official fuel economy of 67.3mpg.

The technical changes that have made this possible include revised piezo-electric fuel injection nozzles, which now have a more precise spray pattern for better combustion and up to 15 percent less unburnt fuel. There is also a new, more responsive, low-inertia variable geometry turbocharger fed by a more direct – and more efficient – air intake path.

In addition, a closed-loop low-pressure exhaust gas recycling (EGR) system, in which the exhaust gas is cooled before being re-introduced to the intake system, has helped ensure the unit is compatible with next year’s Euro6 emission regulations.

The gear ratios have also been changed. First and second have been shortened slightly for better low-speed responses, while the higher four have been lengthened. Staying on the drivetrain, a stop-start system helps reduce fuel wastage during longer stationary periods.

Numerous small reductions in internal friction have also contributed to the overall improvements, which correspond to a 14% boost to fuel economy.

The driver can choose one of three Nissan Dynamic Control system settings, with specific throttle maps including a torque-restricted option for enforced fuel saving.

“As well as the obvious advantages of lower emissions and improved fuel efficiency, the higher levels of torque from the new engine mean greater flexibility and more refined cruising as well enhanced in-gear performance around town,” said Paul Wilcox, Senior Vice President, Sales and Marketing Nissan in Europe.