Audi's forbidden fruit: the A5 3.0 TDI ULES

Audi's forbidden fruit: the A5 3.0 TDI ULES

Wheels

Audi A5 3.0 TDI ULES
By: Jim Robinson

NIAGARA-ON-THE-LAKE: First, the bad news. You will probably never be able to buy this car on this side of the Atlantic.

But the good news is the technology behind the TDI (turbo diesel injection) Ultra Low Emission System (ULES) in this Audi A5 3.0 TDI takes diesel propulsion into in a new green era.

Starting in the first quarter of 2009, Audi will begin importing the Q7 luxury SUV with the same 3.0-litre TDI engine as in the A5. The reason for the long lag time is because by that time the more stringent Euro 6 and North American Bin 5 emission standards will be in place. The Bin 5 system is so close to the European one that adapting the TDI for North America will be relatively easy.

The 3.0 TDI in both the Q7 and A5 already meets that standard. In fact, what comes out of the tailpipe is already so miniscule it is threatening to go below the ability of equipment able to detect anything.

Because North Americans associate diesels with economy cars and delivery trucks, wrapping your perceptions around a diesel high performance luxury sports coupe is a bit of a stretch - until you drive the A5 TDI ULES.

In terms of performance, the 3.0 TDI engine develops 221 hp, but more importantly, 406 lb/ft of torque. Torque is what turns the wheels. The more torque, the more powerful the car. And 100 per cent of that torque is available between 1,750 and 2,750 rpm on the TDI.

The A5 3.0 TDI has 40 more lb/ft of torque than a BMW M6, 50 more than a Ferrari F430 and 35 more than a Hummer H2. It goes from 0-100 km/h in just 5.9 seconds with a top speed of 250 km/h.

At the same time it gets an estimated 6.4L/100 km (approx 44 mpg) city/highway combined which is better than some current economy sedans. And the best part is you can expect to travel about 900 kms on one tank.

The system is based on fuel injectors that operate at 29,000-psi (2,000 bar), gas recirculation with two intercoolers and pressure sensors pioneered by Audi that control the combustion process. The turbo with variable vanes adjusts for the best boost depending on load.

It is fed into a catalytic converter where gases are combined with AdBlue, a urea solution, that changes into ammonia with heat and that splits the nitrogen oxide into simple hydrogen and nitrogen.  

The biodegradable AdBlue is carried onboard in a separate container that is replenished at the dealership during routine service appointments. Sensors gauge the AdBlue required. A bonus is the efficiency of the system will remain functioning perfectly throughout the lifetime of the vehicle.

And because the injectors can infinitely and instantly supply the correct fuel/air mixture for the most efficient operation, diesel "clatter" is virtually eliminated. It is aided by the architecture of the engine block that is extensively "ribbed" to quell internal vibrations and is 15 per cent lighter than cast iron due to its use of vermicular graphite cast iron.

What I noticed was how fast the engine starts. Before the TDI, you had to wait for the glow plugs to heat up the cylinder before combustion could begin. Often it was 10-20 seconds before the glow plug indicator light would go out. With the TDI, its Quickstart plugs hit 1,800 degrees Fahrenheit in two seconds.

Besides the TDI Q7 this time next year the longer term plan is to offer the same engine in the A4 compact sedan by 2010-2011. After that, frankly, the biggest problem for Audi may be keeping up with demand. More than half of all Audis sold currently are diesels and the recognition of the advantages of the TDI system has not been lost over here with oil creeping up to (US)$110 a barrel. If the Americans ever embrace diesel, the swing away from gasoline will be like a tsunami.

The A5 is for sale in Europe but chances of seeing it here are slim at least in its current generational style. In the automotive world I've learned never say never. Witness the Chevy Camaro for that.

I drove the A5 TDI ULES in and around the Niagara Peninsula on a combination of three-lane freeway to narrow, snow-covered blacktop winding across the spine of the Niagara Escarpment and down through little valleys with trimmed back vines awaiting the first warming suns of the wine-growing season.

On the highway at 100 km/h the tach was reading 1,200 rpm. Because all that 406 lb/ft of torque start to come in at this point and is all there by 1,750 rpm, passing required the faintest amount of toe pressure on the pedal.

On those country roads, rounding a corner at 30 km/h, just stab the pedal and you could feel the flow of power to the all-wheel-drive quattro system as it dug in with the right amount of power at each wheel and almost thrust me ahead.

This is the kind of response you expect in a high performance sports sedan, but not from a diesel.

The interior is identical to the current A5 with its liberal use of amber nighttime lighting and about the only German infotainment system I can work without having to pull over and read the manual.

I couldn't help imagining what the A5 would be like with the 4.2-litre TDI V8 (326 hp, 560 lb/ft) or the 6.0-litre V12 (500 hp, 737 lb/ft) TDI engines Audi offers in the Q7 in Europe. Watching how Audi builds upward in terms of power from a base model, the A5 4.2 and/or 6.0 TDIs can't be far away.

It's a bit like comparing apples and oranges, but the best handling sports sedan I have experienced so far is the BMW 335i with its twin turbo inline six-cylinder gasoline engine. With its longer legs and quattro drive, the A5 might just have the advantage.

Alas, we will probably never know until the A4 with the same engine comes along in three or maybe four more years.

But, I can tell you; it will be worth the wait.

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