The first details of the power unit within the upcoming Mazda MX-5 have started to unravel: the new lightweight Japanese roadster will be powered by a 1.5-litre SkyActiv petrol engine, sources confirmed to Autocar. Earlier today, Mazda also announced that the Miata will celebrate its 25th anniversary by hosting “the biggest birthday party yet for the storied two-seat roadster” at the 2014 New York Auto Show in April.

The rear-drive platform was designed from the bottom up and integrates the all the solutions produced by Mazda SkyActive program, more specifically talking about the chassis and body that make up the spine to the latest models the Japanese brand. Autocar says, under the hood of the new compact roadster is a 1.5 SkyActiv-G engine, which was recently also put in the Mazda3, that makes 99hp and 111lb ft-torque. No doubt, the 1.5 SkyActiv G will reach a higher state of tune for the new Miata. However, reports insist Mazda will not pursue force induction to find power.

Some readers may recall that the all-new Miata platform is also designed to serve a new Alfa Romeo roadster. According to reports, the Alfa Romeo roadster will have a turbocharged 1.4 liter engine developed by Fiat, as opposed to the naturally aspirated route taken by Mazda. What's more, the Italian sibling will feature a dual-clutch automatic gearbox as well.

However, some reports claim the Italian roadster may not be an Alfa Romeo after all. According to Fiat CEO Sergio Marchionne, Alfa Romeo vehicles must be produced in Italy to protect the brand's premium identity. If the Italian roadster is assembled alongside the Mazda Miata MX-5 in Mazda's Hiroshima plant, then the Italian model may become either a Fiat or an Abarth. The naming of the Italian sports car has yet to be officially confirmed by Fiat and Mazda.