Even this stripped-to-the-bone, one-off MX5 Superlight roadster concept, built for the 2009 Frankfurt motor show, weighed in at almost exactly a ton.

If rumours leaking from Toyo Kogyo's top-secret skunk works are anything to go by, the next Mazda MX5 could just be the lightest yet.

A senior insider let slip that the slide rule sensei have been challenged to slice nearly 330kg off the 1127kg of the current MX5, to bring it down to a target weight of just 800kg.

The idea is to recreate the minimalist character and incredible agility of the original 1989 Miata (which, it must be said weighed 990kg with a full tank of fuel) in a car that can meet 2012 safety standards.

Hmmm... Colin Chapman would have loved it.

It will probably have the 1.4-litre version of Mazda's SkyActiv engine development series, turbocharged, with direct injection and variable cam timing, which would be considerably lighter than the current two-litre mill.

The only problem there would be making a gearbox with a shift action as short and crisp as that of the original Miata - and here's hoping they don't let the search for lightness lead them astray down the path of front-wheel drive.

Sure, it'd probably be lighter but it would kill the MX5 brand overnight.

The car will be distinctly narrower to reduce both weight and frontal area, although apparently this has raised problems with side-impact protection, and forced designers to adopt a pyrotechnic bonnet, a la Jaguar XK, to meet EU pedestrian protection standards.

More weight will be saved by using a lot of high-strength steels and aluminium alloys for the body - and leaving out everything they possibly can.

Expect to see a parcel shelf in place of a glove compartment (why not, Lotus does it) no spare and no owners manual - that'll be supplied on a USB memory stick!

Apparently, not even the product-planning suits at Mazda believe this mind-stretching target can be met, but the next-generation MX5 could well wind up weighing about the same as its 1989 ancestor (i.e. less than a ton) which, with modern crash protection and an acceptable level of comfort, would be a considerable achievement - and a real honey to drive, especially if it's still rear-wheel drive.