The Mazda MX-5 should continue to get even lighter in future generations, with downsized three-cylinder engines likely to power them.

The current, fourth-generation MX-5 was smaller and lighter than the car it replaced. While MX-5 programme manager Nobuhiro Yamamoto has said the MX-5 is unlikely to get smaller in the future (a fifth-generation car won’t arrive before 2021), it should get lighter due to the increased affordability of lightweight materials such as carbonfibre.

“The size is right,” said Yamamoto. “But in the future lightweight materials will be very important and will be used in this car. Now carbonfibre is very expensive, but we have in development affordable carbonfibre, so the MX-5 will be lighter in the future.”

On the subject of downsized engines, Yamamoto said as the car got lighter, the need for a big engine reduced. Mazda has already achieved this, with the current MX-5’s base engine being a 129bhp 1.5-litre unit.

“It’s a simple concept,” he said. “The vehicle weight gets lower, there’s a smaller engine, smaller tyres. It’s a lightweight sports car.”

Yamamoto also revealed that the recent Speedster and Spyder concept versions of the MX-5 were not feasible for production, despite showing the car at its purest.

The pair were unveiled at the SEMA tuning show late last year in Las Vegas, and the Spyder appeared at the recent Goodwood Festival of Speed.

“We have dreams, our customers have dreams,” he said. “An open car is very emotional, and you have a good feeling driving this. But it’s not feasible and is a very difficult car [to make]. It’s a dream car.”