Diesel technology in the luxury car segment is nothing new. For example, BMW turned heads in 2003 when it introduced its E60 530d. Its quiet, common rail-injected, 230hp, 380-plus NM engine (unusual for a diesel engine at the time), controversial styling and unique iDrive feature made it a success.

However, the German marque had problems with the local diesel fuel, claiming the diesel here was "dirty". 530d owners soon frequented dealerships for repairs and cleaning due to clogged injectors, intake manifolds and cylinder heads. The never-ending rise fuel price hikes also took its toll on repair costs, further damaging diesel fuel potential in the said segment Audi took advantage of this and introduced in mid-2006 turbocharged diesel versions of its A4 and A6 sedans. It boldly claims that it can get 19 kilometers per liter (on normal driving) yet retain the quickness, flash-bang turbocharging and whopping torque derived from its 2006 24 Hours of Le Mans-winning R10 race car. Impressed by the said claim and a need to test its race heritage are the reasons for today's test drive.

Looks fast

Outside, the B7 (chassis code for the new A4) displays a willingness to go fast and look good, even when at rest. The new grille looks like a gaping maw built to suck in huge amounts of incoming air for the A4 2.0L TDI's (turbo diesel injection) slug or turbo, accented by the sleek headlights and the four-ring Audi logo. The sides remind you of a shortened A6, while the rear (especially the right hand side badge) makes onlookers know that it's diesel-fed.

Inside, it's typical German luxury. The cabin is all gray (or grayish back, whichever color you prefer) with aluminum trim serving as the "beltline" or as a divider. Fit and finish are excellent, with the thick doors closing with a muffled "clunk" so distinct of German luxury cars. The dash is expansive that one could put his/her feet on the dash and not feel cramped. The cabin can handle five to six average sized Filipinos in relative comfort, and the leather seats are very comfortable. All windows have one-touch power assist, and the audio entertainment rivals the Chrysler 300C's Boston Acoustics sound system in terms of topnotch listening pleasure.

There are numerous places for storage in the A4, including the cavernous glove box. The rear seats fold flat, and the trunk swallows seven to eight pieces of medium size travel luggage. Speaking of the trunk, the boot lid comes with a huge and easy-to-see early warning device attached.

However, certain features come lacking. The driver's seat doesn't come with power-assist seating adjustment. The trunk lid release button is hard to find. The side mirrors don't have a power-assisted folding feature. And despite the numerous storage places in the car, storage in the door areas (and the area between the front occupants) is quite small.

Le Mans-bred performance

The A4 has a single overhead camshaft (SOHC) 2.0L TDI engine puts out 140 hp and a whopping 320 NM of torque, derived from the R10 racecar that won the 2006 LM P1 (the highest prototype division) section of the 24 Hours of Le Mans. At low rpm the A4 outruns gas-fed larger displacement executive sedans (such as the 3.0L Accord) from standstill starts due to the engine's 18:1 high compression ratio.

A unique feature of the TDI performance is variable geometry turbocharging, so-called because the turbo blades are positioned at double-digit degree increments, thus changing the surface they present to the exhaust gases. This minimizes turbo lag (rotational inertia experienced by the turbo blades when little or no exhaust gas passes through the turbo), kicks in at lower engine speeds and provides faster velocity. In the A4, the Borg-Warner unit kicks in at roughly 3250-3750 rpm and pulls the A4 to a (Laguna) tested 201 kph top speed.

Helping the 2.0L TDI's engine get all its power and torque to the ground is a seven-speed continuously variable transmission (CVT) that Audi calls Multitronic. The Multitronic shifts smoothly, but the last two gears are a little bit taller than its first five gears. Regardless, the CVT always makes sure that the tranny (transmission) stays in one gear or another during mountain passes. And if you wish to access the Multitronic's manual feature, just step on the brake, press the gear selector button, place the gear column to "D (Drive)" and move the stick column to the right. To upshift one has to push the column upwards, while pushing the column downwards makes the car go down a gear. If one is confused, the big menu screen on the easy-to-read dashboard (between the tachometer and speedometer) tells you the gear you have selected for quick reference. Even if you don't shift to first gear in time to make a full stop (like if you need to stop from 60 kilometers per hour to zero quickly), Multitronic does it for you quick and easy.

Steering is heavy yet precise, but not as heavy as the Volvo V50's. The electronic stability program or ESP (designed to maintain directional stability on uneven surface areas) has a default "off" setting, and only turns on when oversteer or ploughing (severe) understeer occurs. Handling is great and the A4 is stable at any speed, but the lack of grip from the Dunlop Sport 01 205/55R16 tires tend to hamper suspension performance. But the brakes grab hard when pressed and the ABS (anti-lock braking system) goes on with little fanfare.

Concerns about the diesel engine and its use here were put to rest when this writer loaded some nine liters of Petron diesel into the car. No check engine light came on, no knocking or pinging happened when the engine was running, and no engine "hiccups" occurred. And this writer got nine kilometers per liter (km/l) on two days of normal city driving and 12 (km/l) on 1.5 days of normal mixed driving. It may be well short of its advertised 19 km/l, but the advantages of diesel in a luxury car are obvious.

Thriftiness, flash-bang turbocharging, several luxury features, bulletproof diesel internals and lightning quick acceleration make the Audi A4 2.0L TDI worth its Php 2.79 M pricetag, with all these and more making the car arguably TDI - The Diesel Ideal.