Engine downsizing, a major trend in European diesel engines over the past decade, will now occur with petrol engines which will increasingly become smaller and turbocharged, a new report said.

"This trend will also have a positive impact on the demand for technologies supporting downsizing such as turbochargers and variable valvetrain," report author Frost & Sullivan said.

It found that suppliers with complete powertrain development and benchmarking capabilities would gain significance.

“Due to comparatively lower CO2 emissions, diesel engines will not face a challenge in complying with CO2 limits; hence, the limitations in downsizing diesel engines will not be an issue,” said senior research analyst Bharath Kumar Srinivasan.

“Reducing the level of downsizing will also help control NOx emissions from these engines, which are being tightened for Euro 6 [emission laws to be enforced in 2014].”

F&S reckons the number of cylinders in petrol engines is likely to decrease only for engines below 1.2 litres. About 35-38% of petrol engines are likely to be turbocharged by 2018. This high level of turbocharging by European automakers is likely to help in the market growth of boosting technologies.

Legal regulations and end-consumer environmental awareness will motivate the sales of vehicles with small engines. For example, the car scrappage schemes in 2009 reduced the average displacement of engines in western Europe. Such initiatives will help boost engine downsizing.

The addition of supporting technologies such as turbochargers and variable valvetrain technologies are expected to drive costs and this is likely to impact take-up rates in cost-sensitive segments.

Downsizing engines results in lower torque output from the engine and, hence, lower transient response. Variable geometry turbocharging (VGT) is a good solution for better torque output, however, introducing VGT at a low cost for petrol engines will be a challenge.

“In diesel engines, aggressive downsizing results in higher specific load and, therefore, increased NOx emissions,” said Srinivasan. “This, in turn, will have an effect cost as NOx after-treatment technologies such as SCR are expensive.”

Automakers are likely to experience higher sales of low CO2 emitting vehicles and thus pass on the tax benefits to the buyer. This offers excellent scope for selling low emission models such as Ford Focus, Volkswagen Polo, Volkswagen Golf and Opel/Vauxhall Corsa.

“With improved emissions and performance, without a drop in fuel economy, being the key drivers, engine downsizing is all set to have a major impact towards achieving CO2 emissions of less than 120g/km in two-thirds of new car sales by 2016,” Srinivasan said.