FEB 09th 2015

Talking rotary engines and the 787B (and snow chains!) with the new Mazda MX‑5's programme manager


At the recent launch event for the new Mazda MX-5, we spent time with programme manager Nobuhiro Yamamoto. During his 40 years with the company, he has spent a lot of time working on rotary engines – including that in the Le Mans winning 787B.  

What was foremost in your minds when designing a new MX-5?

An MX-5 has to be a car that anyone can have fun with. We wanted to create a car that really good drivers will understand and enjoy, but one that normal drivers can get pleasure from too. We looked around and we saw cars getting bigger and heavier, and we wanted to strip things back, to get back to the lightweight principles that guided the original MX-5.

The fourth generation MX-5 is the smallest yet, 55mm shorter than even the original 1989 car, and almost as light. How have you managed that?

The wheelbase is slightly shorter, but the key to the compact length was reducing the overhangs, not compromising cabin space or luggage room. And by shortening those overhangs, and using aluminium for the bumper reinforcements, we’ve reduced and centralised the car’s mass.


How important was it to have a manual transmission? The trend seems to be for fewer sports and performance cars to offer manuals.

The manual transmission is absolutely core to the appeal of the MX-5. Changing gear is something you can get pleasure from at all speeds, not just when you’re going fast. Obviously there is demand for an automatic version, and in places like the Japan the market is strongly in favour of automatics, so we will offer one, but for us the manual is definitely the choice transmission [and will be the only one offered in the UK] and here to stay.

But one of the reasons for the shift to dual-clutch transmissions is that they return lower figures in EC fuel consumption tests. Doesn’t that create pressure on the engineering team?

[Laughs] I’m not going to have someone complain that the new MX-5 is no fun to drive, and all I can say in return is that we saved a few grams of CO2!

A throaty induction roar is one of the most enjoyable things about the 1960s British sports cars that inspired the MX-5. The new 1.5 sounds pretty purposeful, but we’re you tempted to use modern trickery to make it sound like it was sucking through a couple of side draught Webers and pipe it in through the speakers like BMW does?

The MX-5 is all about purity. It’s all real. We wouldn’t have fake sounds so we worked hard to tune the natural sound of the engine. We changed the exhaust system, which now has equal length headers, and we even added some weight to the rear diff carrier because that has a bearing on sound too.


There are two engines, a 129bhp 1.5 and a 153bhp 2.0. How would you describe the difference in character?

The 2.0 is perfect for wide-open spaces and faster corners, or when you’re travelling longer distances, but the 1.5 is the best for really winding roads. My personal favourite is the 1.5. It’s the real embodiment of everything the MX-5 stands for.

We notice this car sits nice and low to the ground, like a sports car should, unlike the last car, which seemed to be taking inspiration from a late 1970s rubber bumper Midget. What’s changed?

We have to leave clearance for snow chains, and when we were developing the third generation car in about 2001, the chains were very bulky. But this car sits lower, and the driver is lower too. We mounted the engine close to the ground, reduced the height of the scuttle and were able to seat the driver closer to the ground for a proper sports car feel.


You spent much of your 40 years at Mazda working on rotary engines and were the man responsible for the rotary engine in the 787b that won Le Mans back in 1991. Does the rotary still have a future with its reputation for wear and high fuel consumption? The rumoured new RX-7, perhaps?

I can’t really comment too much on this. We still believe in the rotary, but it’s an engine that isn’t suitable for all applications – it needs to be reserved for a special car…

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