YOU could argue the midlife model amendment for BMW’s nearly-four-year-old 3 Series Coupe and three-year-old Convertible has arrived just in time, what with the all-new E-class Coupe and Cabriolet from Mercedes-Benz now commanding a dominant 25 per cent share of premium sportscar sales in Australia and Audi’s ever-expanding A5 Coupe, Cabrio and now Sportback range attracting 20 per cent of buyers this year.

Caught in a pincer movement in between with a 23.5 per cent share of the lucrative sales segment – down from a seemingly unassailable slice of almost 30 per cent at this time last year - BMW’s ever-green two-door 3 Series models appeared in desperate need of a freshen-up in the face of accomplished new German rivals.

That’s precisely what BMW has now delivered in the form of a new-look 3 Series Coupe and Convertible range, which also gains small but significant efficiency gains for the ($1900 cheaper) base 320d diesel, M3 hero models and upscaled, more expensive 335i M Sport turbo-petrol models, with nominal price rises in between for the 325i and 330d.

Of course, there’s also a host of new wheel, exterior colour and interior trim options, plus the obligatory new bumper treatment and LED headlight elements, which are standard only on 335i models. But while sat-nav continues to be standard from the 325i upwards, CD stackers have been relegated to the options list for all variants, replaced by a USB input and single-CD head unit.

More importantly, BMW has also addressed the two-door 3 Series’ only real shortcoming when it comes to the driving experience by fitting upgraded shock absorbers to improve low-speed ride comfort on all but the M3 and 335i Convertible.

All of BMW’s latest 3 Series models are at the top of their respective trees when it comes to handling dynamics and that hasn’t changed with the 2010 two-door models, which continue to deliver class-leading steering and road-holding.

But the move to disc-spring - rather than coil-spring - damping valves has made a discernable improvement to the most popular 3 Series Coupe and Convertible models, which have copped plenty of criticism for their brittle ride quality on pock-marked Australian roads but are now much easier to live with both around town and on the open road.

If you want proof, simply drive the entry-level 320d Coupe back-to-back with the 335i Convertible and witness the difference, as we did at last week’s press launch on bumpy Queensland back-roads. Only four-cylinder turbo-diesel and six-cylinder turbo-petrol models – in both fixed-roof coupe and folding-hardtop convertible guises - were made available to us because, BMW said, they come with the biggest changes.

Meaningful peak power and torque increases and the fitment of a fuel-saving idle-stop system for the newly available manual version undoubtedly make BMW’s already-brilliant 2.0-litre turbo-diesel engine in the 320d – which now produces an astonishing 135kW and some 380Nm of torque – even more flexible and efficient. Heavy six-speed manual shift action aside, the 320d is an absolute to delight to punt quickly, not just for a diesel.

But the most noticeable change is its more compliant ride on surfaces that are less than autobahn-smooth. Unlike the vastly heavier 335i Convertible, whose folding steel roof lowers and raises in a tad over 20 second but won’t do so on the move like the A5 and E-class, the most basic 320d Coupe remains unruffled over broken surfaces, even on optional 19-inch alloys and stiff run-flat tyres, which remain standard on all models.

The 235kg-heavier 320d Convertible feels a little softer and changes direction slightly less precisely than the pin-sharp 320d Coupe, but neither model crashes over road lumps and holes like the 335i Convertible, which goes without the revised suspension tune and weighs a massive 330kg more than the 320d Coupe.

Yes, the 335’s new twin-scroll single-turbo petrol six is slightly lighter, more efficient and feels like it delivers better midrange response than the identical-output twin-turbo engine it replaces – and we love the new M3-style steering wheel shift paddles.

But with now-standard M suspension the new-look 335i M Sport Convertible, in which we found ourselves constantly seeking out the smoothest section of road and gritting out teeth when forced to travel over even the most minor surface irregularities, is the least impressive of all the facelift two-door Threes.

Thankfully the firmer and 15mm-lower M suspension tune is a delete option for all 335i models, but those that demand a top-shelf 335i Convertible (which in this case continues to offer almost the best of both worlds with a whisper-quiet folding steel – rather than fabric – roof that gives it coupe-like body rigidity but still allows some steering column deflection) will miss out on the new-found suspension suppleness offered by lesser models in the 320d, 3251 and 330d.

For some reason, nor was either the 335i M Sport Coupe or Convertible’s overly thick-rimmed M steering wheels, matched with that intoxicatingly quick and rewarding turbo-six, as confidence-inspiring as the steering in the better-sorted 320d, thanks to its slightly springy, uneven weighing especially in a straight line. The taut 320d Coupe would glide unflinchingly over road obstacles that would see the 335 Convertible crunch, skip and activate its stability control system with surprising regularity.

Like the 320d manual, the 2010 M3 Coupe and Convertible – which were not available to drive at the launch – come with idle-stop tech, this time for both manual and dual-clutch M-DCT auto versions, making the finest performance model BMW has ever produced even more efficient, even if they do miss out on the garden-variety models’ latest suspension tweaks.

The latest M3 two-doors also lose the EDC electronic damping adjustment and M Drive driver interface systems that were previously standard, which BMW Australia says brings them in line with the M3 sedan, but the M3 Coupe’s handy $4600 price and standard spec reduction is an obvious response to the success of Merc’s more affordable C63 AMG.

For the record, the latter increased in price by more than $2000 on July 1, bringing the auto-only C63 AMG sedan pricetag to $150,980, which is now within $2000 of its most direct rival in the M3 sedan ($152,300) and, in the absence of an E-class AMG coupe, $7320 less than the upgraded M3 Coupe manual ($158,300).

There’s no doubt the 3 Series Coupe and Convertible were in need of an update and BMW could have done more.

But you could also argue that the subtle price, spec and styling revisions across the range, the significant efficiency and driveability upgrades at both ends and the highly effective improvements to ride quality on the top-selling models is all BMW needed to do to keep the 3 Series on top of the mid-size luxury coupe and convertible game.