We usually cover our own travel costs, but in this case, that was not an option; flights and two nights' accommodation on this trip to Palm Springs were paid for by Audi.

A little over a year ago, we traveled to California to sample the new Audi A4. The car's combination of excellent semi-autonomous driving tech and that Virtual Cockpit really appealed to our inner nerd. But the A4 is meant to sell in volume, a bread-and-butter model never meant to set the heart a-flutter. That job belongs to the S4, a hotter version with an extra hundred horsepower on tap. Together with the closely related S5 coupe, it's starting to arrive on these shores, which is how we found ourselves among the mountain roads of southern California once again.

Jonathan Gitlin

Audi

Jonathan Gitlin

Jonathan Gitlin

Jonathan Gitlin

Jonathan Gitlin

Jonathan Gitlin

Audi

Audi

Jonathan Gitlin

A new engine

The S4 certainly breathes more than the sedan it's based on. It's also no track-bred monster; for that, we need to wait for the forthcoming RS4. But it gets a new turbocharged version of the company's dependable 3.0L V6, which replaces the supercharged V6 that's found under the hood of many Audis, including the last generation S4. It features a twin-scroll turbo inside the engine's V (i.e. on top of the engine block between the two banks of cylinders), and Audi tells us that this makes for very short runs for the gases and, therefore, less turbo lag. The new engine is also much more powerful than the outgoing S4's: 354hp (260kW) and 369lb-ft (500Nm), in fact.

The engine is paired with an eight-speed automatic transmission made by ZF, and it's quite similar to the transmission in the RS7. Audi says it picked a torque-converter over a dual-clutch gearbox for the S4, as this engine-gearbox pairing is less jerky at low speeds. Don't get your hopes up for a manual, though. The stated reason? Far too few buyers worldwide to justify the engineering expense. But the fact is that the ever-growing suite of advanced driver assists doesn't play well with three pedals. (The implications of that fact for people who enjoy driving bear thinking about, but at a later date.)

As a tire company once said, "power is nothing without control," and to that end, the S4 has a few other notable tweaks from the base car. It rides 0.9 inches (23mm) lower. Unsprung weight has been reduced in the suspension. As standard, the S4 uses uprated dampers, and adaptive dampers are available with the S Sport package. (These are conventional valved affairs, not magnetorheological.) Tick that box—a $2,500 option—and you also get red brake calipers, but more importantly, you get the sport differential between the rear wheels.

This replaces the standard electronic differential, which uses the car's brakes to slow the inside wheel in a turn. Instead, it's a clutch-based system capable of torque-vectoring, similar in concept to the clever unit found in the Focus RS. We've tried cars with Audi's sport diff before, and it has impressed, but this one is revised and allegedly much quicker responding now. The default torque split, as with the normal A4, is still 40 percent front, 60 percent rear (although it can send up to 70 percent to the front wheels or 80 percent to the rears.)

I’m paying for more than go-faster parts, right?

The cheapest S4 starts at $50,900—$16,000 more than the standard A4. So in addition to the uprated powertrain and suspension, you also get a 19-speaker Bang & Olufsen sound system, Alcantara door panels, a flat-bottomed steering wheel, and eight-way adjustable sport seats, trimmed in a fetching diamond-stitched leather. The seats will also massage you on command and will heat you in the winter. (Seats that cool you in the summer are available as an option.)

The Premium Plus trim also requires you to spend some money if you want the Virtual Cockpit display. That comes standard with the more expensive Prestige trim S4 ($55,800), and you need to go for this one if you also want the semi-autonomous driver assists. That's an additional $1,800, but it does get you one of the best systems on the market right now. So equipped, the car will make light work of long highway cruises; the lane-keeping assist keeps the car well-centered in its lane, and traffic-jam assist takes much of the pain out of traffic gridlock.

On the outside, there are a number of clues that the car you're looking at is an S4. As with all "S" Audis, the wing mirrors and rear diffuser are matte silver—the company calls this "alu-optic," meaning it looks like brushed aluminum even if it's actually painted plastic. The front bumper has more aggressive air intakes (also accented in alu-optic). But the biggest giveaways (other than the S4 badging, obviously) are the 18-inch five-spoke wheels and the fact that it has four exhaust pipes.

Hey, didn’t you say there was a coupe?

The S4 (and A4's) MLB Evo platform also forms the foundation for several other models in Audi's range. Shortly after the A4 debuted last year, we got the A5 coupe and A5 convertible, and then at last year's LA Auto Show, the company took the wraps off an A5 Sportback. All three of those body styles are available as an S5—although the Sportback won't reach us until later this year.

Jonathan Gitlin

Jonathan Gitlin

Jonathan Gitlin

Jonathan Gitlin

Jonathan Gitlin

According to Frank Lamberty, the car's designer, the S5 is a more emotional-looking machine than its S4 sibling. The LED headlights are different, the grille is lower and wider, and the hood has different creases and lines, in keeping with a car that's meant to be more GT than sensible sedan. It's lower (1.4 inches/36mm) than the S4, and shorter both in overall length (2.1 inches/53mm) and wheelbase (2.4 inches/61mm), but it's ever so slightly wider (0.2 inches/4mm). The coupe S5 is also 22lbs (10kg) lighter, although both vehicles have the same drag coefficient (0.29).

The new S5 coupe replaces what was arguably one of Audi's best-looking models, and while the interior (which is almost identical to the S4, even down to the driver's seat H-point) is a big improvement on the previous S5, we don't think the new one's exterior cuts quite as dashing a figure. You obviously lose some rear leg room in the two-door car—about three inches—and luggage space is slightly reduced (11.3 cubic feet/319L vs 13 cubic feet/368L).