The co-developed new Mazda MX-5 and Alfa Romeo Spider will each be sold with its own, bespoke engines, with even a diesel unit being a possibility for the MX-5.

Mazda intends to fit its version of the upcoming MX-5, due next year, with a new naturally aspirated SkyActiv engine as the staple unit. It is likely to be 1.6 litres in capacity, with an output of around 130bhp.

The Spider will probably use Alfa’s turbocharged 1.4-litre ‘TB’ engine. More powerful MultiAir or 1750 TBi units, the latter as found in the 4C sports car, may also be offered. Power could range from 120bhp for entry-level Spiders to 296bhp for top-end cars.

Mazda is insistent that the MX-5 will remain naturally aspirated, but turbocharged versions of previous-generation MX-5s have been produced. Alternatively, to provide more power without resorting to forced induction, a larger SkyActiv engine could be fitted.

A diesel option is being considered, but the lightweight and high-revving capabilities of a petrol engine are more desirable to Mazda. There are also concerns over the market viability of a small diesel roadster, which might prove difficult to sell.

It’s likely that a six-speed manual gearbox will be available for both cars, while an advanced paddle-shift six-speed auto could be offered.

Mazda hopes the new car will be the same size as the original MX-5. Modern materials and design techniques will help to reduce weight, while meeting modern crash regulations. This will help to achieve Mazda’s ambitiously low target weight of 800kg.