New Mazda MX-5: More secrets revealed

It was the best-kept secret about Mazda's third-generation MX-5, but we now have definitive information from a source close to Mazda about the new roadster's tightly guarded kerb weight and engine outputs.

When Mazda executives said they were going back to basics with their latest ND-series soft-top — back to the dimensions and specs of the original NA-series of 1989 — they weren't kidding.

It's now on record the MkIII MX-5 is in fact smaller than the 25-year-old original. In fact, at just 3915mm long, it's a full 105mm shorter than the current NC-series and 35mm shorter than the NA, although it's 55mm wider and 50mm longer in wheelbase.

Despite making global debut last week, full details won't be announced until its motor show premiere at next month's Paris motor show, before it is launched internationally early next year and goes on sale in Australia in the second half of 2015.

But in a surprise revelation, our source has revealed the new MX-5 will tip the scales at 1020kg, meaning Mazda has achieved its stated goal of reducing weight by up to 100kg, thanks to greater use of aluminium (now for the guards, bonnet, boot lid and bumper brackets).

Given Australia's outgoing NC-series MX-5 Roadster Coupe manual weighs 1167kg, the entry-level ND-series MX-5 soft-top will in fact be almost 150kg lighter than its direct predecessor.

Of course, Australian specifications have not been confirmed and may vary from the circa-1000kg figure, which is just 40kg more than the first MX-5 (980kg).

This is despite the addition of more safety and convenience features, including Mazda's MZD Connect infotainment technologies, including a seven-inch colour touch-screen with Bluetooth connectivity and sat-nav, speakers in the head restraints and LED lights all round.

The other juicy piece of news from our insider is that entry-level versions of the car will be powered by a 1.5-litre SKYACTIV four-cylinder petrol engine producing 96kW.

Again, Australian specs are yet to be announced, but that's a reduction of 22kW from the outgoing model, which offers 118kW/188Nm from a larger 2.0-litre engine (and up to 125kW in Japan), but the 19 per cent weight reduction should more than compensate for the 13 per cent lower power output.

A torque figure for the new MX-5's downsized 1.5 remains under wraps, but it should produce more than the 144Nm delivered by the highest-output (85kW) Asian-spec version of the same engine in next month's new Mazda2.

For the record, our new Mazda2 will come with two versions of the new 1.5-litre four, both with more power than Europe's 55kW mill but lower outputs and compression than Japan's engine, which has a 14.0:1 compression ratio.

To cope with our 91 RON standard unleaded petrol, we'll get a 79kW/139Nm job with 12.0:1 compression and four-into-one exhaust, and an 81kW/141Nm version with 13.0:1 compression, four-two-one exhaust and better fuel economy.

The same engine produces 82kW with 13.0:1 compression in Japan's base Mazda3, but Mazda has tuned it to generate more power at higher revs – with a 13.0:1 compression ratio, so chances are we'll also get the most powerful 96kW version in our MX-5.

We understand was also testing 1.6- and 1.8-litre powerplants for the entry-level MX-5, but opted for the 1.5 because it offered “the best balance of power and fuel economy”, according to our source.

Either way, notwithstanding its smaller displacement, which could create significant marketing hurdles for Mazda, the new MX-5 should deliver an improved power-to-weight ratio even at base level.

"We will be able to use a smaller, less powerful, more fuel-efficient engine because we will have shaved so much off the current car's kerb weight," insisted one engineer at the launch in Tokyo on September 4.

Our source also said the first all-new MX-5 chassis since the original (the second-generation MX-5 was based largely on the first, while the third shared its roots with the RX-8) will bring vastly improved dynamics.

The first rear-drive application of Mazda's latest SKYACTIV chassis, which could also underpin other models including the long-rumoured 2017 RX-7, is not only smaller but carries revised suspension and, for the first time in an MX-5, electric power steering.

“A repositioned drivetrain will deliver better weight balance and improved handling dynamics, giving you a better driving experience. And believe me, you will not notice the drop in power from the current version.”

As expected, however, there will be a larger 2.0-litre SKYACTIV engine, but our information is it will follow the launch of the initial 1.5-litre MX-5 by up to a year.

Whether it arrives in time for Mazda Australia to launch the new MX-5 here with both engines remains unknown, but the 2.0-litre four should bring substantial improvements in performance over both the 1.5 and the outgoing 2.0 – given the Mazda3's 2.0-litre engine offers 114kW/200Nm (slightly less power but more torque than current MX-5).

Once again the next MX-5 soft-top will eventually become available with a retracting hard-top roof, which will also bring more weight — but it should still be the quickest, fastest MX-5 since the long-lamented turbocharged SE and SP variants.

Perhaps more importantly for some, the new MX-5 will be the cheapest for quite some time . After becoming a hard-top-only model here in 2008, the NC Series II is currently priced from $47,280.

But the soft-top, smaller engine and standard 16-inch alloy wheels will reduce the new car's base price significantly, to less than $40,000.