Toyota Yaris upgraded with new more powerful 1.5-liter petrol engine

First, in early December, the Japanese manufacturer revealed its competition-prepped Yaris, which made its first appearance in the World Rally Championship last weekend. Less than a month later we saw a hot, WRC-inspired Yaris with "more than 210 horsepower (156 klowatts)" in first official images. And now there's a new 1.5-liter, naturally-aspirated engine for the standard Yaris.

The four-banger is effectively replacing the 1.33-liter unit from the current lineup, offering more power and higher efficiency. With 110 hp (82 Kw), it is has 12 hp (9 kW) more and also a higher torque peak at 101 pound-feet (138 Newton meters). The motor will be produced in Poland as part of a $161-million investment and will deliver "better performance and a more enjoyable drive," while at the same time achieving a reduction of up to 12 percent in fuel consumption, under the current NEDC official test criteria.

The Yaris 1.5 will need 11.0 seconds to cover the 0-62 miles per hour (0-100 kilometers per hour) sprint – 0.8 seconds faster than the Yaris 1.33 it replaces. The new engine can switch from the Otto to the Atkinson cycle to "gain optimum efficiency in different driving conditions," which results in 38.5 percent thermal efficiency value, "among the best on the market."

Interestingly, the new unit has been optimized not only for urban use, but also for motorway trips. For the first time Toyota is introducing a water-cooled exhaust manifold, which limits the gas temperature, avoiding the need for mixture enrichment to reduce combustion temperature at any motorway driving speed. As a result, both fuel consumption and exhaust emissions are reduced, the company claims.

Needless to say, the 1.5-liter unit also benefits from Toyota's VVT-iE technology, a variable inlet valve timing system. In its newest version, it uses electronically controlled intake valve and hydraulically controlled phase shift of the exhaust camshaft.