2010 Audi S4 review

Audi just can't seem to make up its mind about the S4.

First, it was powered by a puny 2.7-litre V6 juiced up to 265 horsepower with the addition of two steroid-like turbochargers. In 2003, in an effort to compete with the Joneses (in this case, BMW), it was determined that two extra pistons had a whole lot more cachet than two turbochargers. Hence, until very recently, the S4 was powered by a 4.2-litre V8.

But small-displacement V8s need to rev to make power and, as glorious as all that cacophony may be, high engine speed equals high friction — anathema to fuel efficiency — and in these environmentally conscious days, even a pocket rocket has to be as green as possible.

The answer was a return to a blown engine (forced-induction engines can be smaller and don't need to rev as high to make power, both boons to fuel economy). But, this time, instead of twin turbochargers, Audi has plunked a single Eaton Roots-type supercharger inside the engine bay to force feed the now 3.0-litre V6.

It's made all the more confusing because the S4 wears the "T" badging (as in V6T) usually reserved for its turbocharged cars. Not only that, but the supercharged 3.0L takes a step backward in the horsepower department, boasting only 333 h.p., while the outgoing 4.2L had 340.

Of course, Audi is not in the business of making successively worse — or slower — cars, so there's more to the new S4 than a slight loss in horsepower. In fact, thanks to the benefits of supercharging, there's 23 more foot-pounds of torque — 325 versus 302 — from the V6 than the V8.

Perhaps more importantly, that torque peak occurs at a much lower 1,500 r.p.m. with the blown V6.

If you're thinking that makes the new S4 gutsier at low speeds, you're right. Immediately noticeable is that the 2010 jumps off the line where the previous V8 version needed to gather revs before it gathered momentum. Audi says it scoots to 100 km/h in just 5.1 seconds, a breath quicker than the outgoing V8. It's definitely more responsive.

Having tested the base version of the supercharged engine in the new A6, I did, however, worry that the V6's rather nasal exhaust tone would be a real step down from the exciting whirrings of Audi's high-revving V8. But somewhere in the transition from dowdy luxury sedan to über sports sedan, the blown V6 gained some much-needed character.