Mazda 6 MZR-CD v Volkswagen Jetta 2.0 TDI 2007 Comparison

A funny thing happened on the way to the servo. During this comparo, diesel went (in Sydney at least) from costing more than ultra unleaded 98, to costing a little less than regular petrol. The price has since risen to hover above premium unleaded, but that's unlikely to slow the galloping surge in diesel passenger-car popularity… an area the Mazda 6 MZR-CD and Volkswagen Jetta 2.0 TDI are right in the thick of.

Although the 6 and Jetta may seem an odd couple - one is as diligently Japanese as the other is overtly Germanic - they are in fact a closely competitive pair. Despite some telling differences, they cross swords in many ways.

Consider pricing, for example. You may think that the Jetta draws first blood by costing $35,690 as a six-speed manual, whereas the Mazda asks $38,090. In fact, far from being wounded on price, the Mazda gives its rival a few good licks. For one thing, the Mazda is a five-door with a large, sloping rear hatch, whereas the Jetta is a garden-variety sedan. For another, the 6 has no-cost metallic paint ($690 extra for Jetta), full (perforated) leather trim throughout and an electrically adjustable driver's seat ($3990 extra in the Jetta). Importantly for some, the VW offers DSG auto-manual transmission ($2300), while the Mazda is strictly manual. However, the 6 diesel also available as (cheaper) wagon, for which VW has no direct answer.

Curiously, the Jetta has no badges to identify it as a 2.0 TDI model, whereas MZR-CD is writ bold and bright on the Mazda's front doors; just above the bodyside protector mouldings which the Jetta also lacks. Regardless, the engines let their grunty performance and thrifty economy do the talking, or the torquing as the case may be. They share nominal 2.0-litre capacity, have twin-cam, 16-valve alloy heads, and inject fuel directly into the combustion chamber.

But that's where the basic similarities end. The Mazda has square (equal) bore and stroke dimensions, where the Volksy is markedly under-square, with the bore diameter much less than the crank's stroke. The VW has the squeezier compression ratio, and its injection is accomplished with the Pumpe Düse method, where each injector includes its own high-pressure pump operated by the intake camshaft. Mazda uses the common-rail system, with the individual injectors supplied from a shared high-pressure reservoir.

There's little difference in the claimed power outputs, the Mazda cites 105kW, just two kilowatts more than the Jetta. More influential, perhaps, are the speeds at which peak power occur, at 3500 and 4000rpm respectively, especially in association with the torque outputs. There the Mazda claims 360Nm to Jetta's 320Nm, which would seem to put the issue beyond dispute. But keep in mind that the Mazda maxes at 2000rpm, whereas the Jetta punches at full strength from 1750rpm to 2500.

That's not the end of the equations either, for the diesels' relatively short rev range means that their gearing plays a significant role in the outcomes. Both six-speed units have good gearchanges - as they should, because there's a whole lot of shifting in store to wring the best from these muscular oilers.

The Mazda's transmission is distinguished by having one final-drive ratio for the first four gears, and another for fifth and sixth. The Jetta's conventional, single final-drive covers everything. Overall, the Mazda is the taller geared, doing 58km/h per 1000rpm in sixth, whereas the Jetta's top gear gives a whisker over 53km/h per thousand. For brisk cruising in fifth and sixth gears, both models have longer legs than Gold Coast table dancers. Yet, while that's great for reducing fuel consumption and noise at speed, it also means sixth is pretty much a write-off below about 75km/h, while fifth starts turning crotchety below 55km/h. Understandably, these gears don't often surface in typical urban driving.

For diesels, however, the Jetta and 6 go pretty good. The silver lining is that while they're respectably accelerative against the clock, their point-to-point performance on the road is more impressive than mere figures may indicate.

In the manner of other manual diesels, the moral is to upshift early and often for acceleration's sake. That also applies for rapid in-gear response, as demonstrated by the pair's laboured fast-start/slow-finish result from 80-120km/h in third gear. There, the Jetta barely reaches 125km/h before the limiter rains on its parade, while the Mazda can (just) be persuaded over 140km/h. Extending them that far wastes time because their real rush is over even before the 4000rpm mark, beyond which the needles' climb takes an age.

In contrast, fourth gear invites the lusty mid-range torque do its thing, and sees the 80-120 increment dispatched quicker than in third, with revs to spare. As expected, the times taper off in fifth and sixth as the engines commence the runs from lower (and lower again) revs. The rivals' difference in low-speed punchiness is accentuated because the Mazda's pedal momentarily feels doughy when flat-footed from 1700rpm - whereas the Jetta gets on the job slightly earlier, with a shade more zeal. Overall, however, the performances are close enough, albeit in different places, to be swings and roundabouts.

Both models weigh about 75kg more than their petrol siblings; not enough to materially dent the performance potential. Nor to adversely affect their driving dynamics. Most of the extra mass is carried by the mildly uprated front suspensions, so the ride and handling are near-as on a par with their acclaimed petrol cousins.

The Jetta feels the lighter of the two on its feet and usually a shade more directional, but the Mazda answers with wonderfully well-balanced and responsive handling that gives its rival no quarter when scampering through twists and turns. Both are mild to middling understeerers through hard, fast corners, but don't feel clumsily nose heavy - they refrain from kneeling on the front-end or scrubbing the tyres. Sloppy bodyroll isn't in their job description either, and they invariably feel securely settled during cornering's forceful lateral transitions.

It's to their mutual credit that the respectively well-disciplined suspensions furnish such consistently talented handling without discomforting the ride to any objectionable degree. The 6's comfort levels are the slightly more supple and absorbent of the two, and soak most disturbances with statesman-like diplomacy. But while the Jetta's comparative firmness often reflects small-bump repetitions, its tolerant absorbency smooths most other irregularities without hint of harshness.

The weighting of the Mazda's steering (like the clutch) is a noticeably meatier than the Jetta's, without any suggestion of heaviness. Although neither provides much steering feel, both have a good sense of connection for accurate response to driver inputs and unwaveringly stable tracking on the straights. Each model's (leather rimmed) steering wheel features height/reach adjustability and spoke-mounted function buttons.

When it comes to stopping, the brakes are up to the job with consistently arresting performance even when the heat's on. However, the Mazda has the better pedal feel overall, with perceptible graduation between driver input and braking response. The Jetta, in contrast, over-reacts to light, low-speed dabs of the pedal, causing a bit more braking than intended.

However, in the Jetta and 6 alike, the most persistent road-going grizzle stems from the frequently intrusive tyre/suspension rumble. It occurs most noticeably in the Jetta on coarse-chip surfaces, and in the Mazda over small, otherwise almost imperceptible washboard ripples. Added to the noticeably growly engine noise (that's a constant, if varying, accompaniment except when light-throttle cruising turns conspicuously hushed), the frequency and volume of road noise means these aren't quiet cars, even against some diesel peers, let alone most similar petrol models. The only thing going for the gravelly engine noise is that if you're attuned, it lends a distinctively diesel character to the cabin ambience.

And ambience is something both enjoy. The Jetta's cabin is the more compact of the two, and looks/feels it due to less shoulder width, higher window sills and cowl. Although the VW affords ample knee room for adult rear passengers, the 6's extra cabin length shows the benefit of a wheelbase about 100mm longer than its competitor's.

The rivals are close to line-ball for other features and equipment, except that the Jetta includes an auto-dim interior mirror, rain sensing wipers, air-conned glovebox, tyre pressure indicator and rear parking sensors. And heated door mirrors. The Mazda omits those items, but includes front fog lights which are optional for Jetta.

So, when everything's assessed, which will do? It's so close that the picking's down to personal preferences. The vote could go either way, and you'd be on a pretty good thing regardless of which one noses ahead. But before your mind's finally made up, give a serious second thought to the fact that each model harbours a glaring shortfall which may or may not affect your verdict.

To comment on this article click