Is Smaller Better?

What is it about small-but-quick cars? They're exceedingly popular, both in convertible and hard-top varieties, and the market segment isn't showing any signs of abating.

Take a look at Mazda's MX-5, or Renault's Clio Sport for a good example - they sell by the ship-load because they're affordable and they appeal to the eye.

Their short wheelbases and rigid chassis also gift them with very nimble and indeed confidence-inspiring handling capabilities, while their small size makes navigation and parking a breeze, and compact engines help reduce fuel consumption.

Daihatsu and Mazda have always been keen on the small car, and perhaps these relationships could even be described as love affairs, such is the commitment.

This devotion to small and increasingly sporty vehicles is clearly illustrated in two new cars from the Japanese marques, both models hinting at future design philosophies and engine technologies.

To start with, Mazda has called its Ibuki concept a "Near Future Concept Roadster," which suggests that a visually toned-down version could hit the roads in the next three years.

Moreover, Isao Tohda (a key member of the Ibuki development team and who also played an important role in the development of Mazda RX-8) said: "Mazda Ibuki is not simply a concept of what the future has in store. It is an ultimate statement of the kind of roadster Mazda could be building before very long."

And it only takes one look at the Ibuki concept to guess which three characters will be adorning the rag-top's flanks: MX-5.

First shown at the 2003 Tokyo Motor Show in Chiba prefecture, the Ibuki keeps many of the current (2003 model year) MX-5's styling cues, such as the short front and rear overhangs and similar overall dimensions.

The snub-nosed front end is more reminiscent of the original 1989 Mazda MX-5, though head and tail lights tell a more modern story and the centrally-mounted split oval exhaust pipes look absolutely gear.

18-inch magnesium alloy wheels fitted with run-flat tyres help reduce unsprung weight, and give the miniature Mazda a more determined stance at the same time.

The Ibuki, whose name comes from a Japanese word that refers to "breathing new energy into" and "adding vigor", is likely to offer even more impressive on-road dynamics than that of the already pliable MX-5, due largely to an improved centre of gravity.

The Mazda design team behind the Ibuki made use of the front-midship engine layout seen in the Mazda RX-8, where the engine's bulk is placed slightly behind the front axle.

Compared to the current Roadster/MX-5, the engine is located about 400mm more rearward and 40mm lower.

Sadly, the Ibuki doesn't take delivery of Mazda's rapid and revvy 1.3-litre rotary engine, but the four-stroke engine used instead will be far from dull.

In keeping with a low-weight theme, the Ibuki concept packs an MZR 1.6-litre, inline four-cylinder engine, with 4-valves per cylinder and sequential valve timing and lift for both intake and exhaust valves.

The engine also gets an integrated electric hybrid motor that improves acceleration and partly serves to control engine vibration, allowing for the use of a lighter flywheel for quicker throttle response. And, like some other hybrid engines, during deceleration the motor functions as a generator, using the heat energy from the brakes to recharge the battery.

All things considered, 132kW @ 7500rpm isn't too shabby for such a small-capacity engine, while 180Nm @ 6000rpm would provide the Ibuki with plenty of shove, particularly when you consider that it's a lightweight roadster, making use of materials like carbon-fibre, aluminium and reinforced plastic.

The hybrid petrol/electric engine is mated to a six-speed manual transmission that weighs less than the current MX-5 gearbox and has reinforced synchronisers to give a decisive yet smooth shift feel.

In an effort to advance safety in open-top vehicles, the Ibuki design team decided to installed a four-point active roll bar into the front pillars and rear cowl section. Simply put, it instantly lifts up under impact sensor control to reduce occupants' injuries in the event of a rollover.

Powerful LED headlamps also give improved visibility, and a now de rigueur keyless entry ID card gives it that future car feel that so many at the Tokyo Motor Show aim for.

Daihatsu, meanwhile, has leaked info for its larger-engined performance model Copen convertible, with engine capacity increased from 659cc to 1300cc - almost double the size.

The top secret performance Copen's name has not yet been divulged, but you can be sure it'll be something annoyingly cute or clever.

In line with the bigger engine, the new performance model Copen gets a slightly lower ride, Recaro racing seats, aero bodykit extras and an oversized spoiler, sports alloy wheels and a mild power bulge on the bonnet.

While the standard Copen weighs 830kg, the sporty model may get a further reduction in weight, though judging by the bodykit addons, unless they're fabricated from carbon fibre this is unlikely.

The new 1.3-litre turbo engine will endow the Copen with a much more decisive personality, as power has more than doubled thanks to the bigger DOHC power plant.

Where the 659cc inline four-cylinder mill made 47kW of power, the bigger 1.3-litre turbo motor makes 103kW @ an as-yet unknown engine revolutions p/minute, but expect it to peak around 6000rpm (a reader points out peak power hits @ 6400rpm, while redline is 7800rpm).

Torque has also increased dramatically from 110Nm to 170Nm, arriving @ 3200rpm in both engines, which should help push its 0-100km/h times below 8.0 seconds.

Such a mighty midget would have been unfeasible in markets outside of Asia five years ago, but as cities get bigger, fuel becomes more expensive and real estate - especially in the Nihon - becomes harder to come by, cars will continue to become volumetrically efficient out of necessity.

And while the sportscar is becoming smaller and smaller, such compact and micro four-wheelers are increasingly being seen as fashionable, chic and very cool. Cars like the Mercedes-owned Smart Roadster, the new performance Copen and even Mazda's Ibuki concept all point towards a future dominated by low-emissions, eco-friendly tiddlers as heavier, larger cars become phased out.