The latest iteration of Audi's S6 mid-size sport sedan leans to relative Lamborghini for a V-10 engine and uses all of the quattro sport division's expertise in usefully converting power to motion. And it does so for considerably less than its primary German rivals.

With the Gallardo's V-10 engine slightly enlarged to 5.2 liters it becomes the largest engine ever to find its way into an Audi 6 series. Like the V-10 in the flagship S8 it is retuned for daily use and not so highly strung as some of its competitors, and since the home market doesn't take kindly to anything going faster than the flagship, the S6 is rated at 15 horsepower less because its maximum engine speed is 200 rpm lower; peak torque is nearly 400 ft.-lb. from 3,000-4,000 rpm with 363 ft.-lb available from 2300 rpm onwards.

Since the S6 gives away 65 hp to the BMW M5 and 72 to the Mercedes-Benz E63, has a gear less (in automatics, the BMW manual is also six speeds) and weighs more than either, it stands to reason it would be the "slowest" of the trio. And in an ideal conditions drag race it is, although at a hair over 5 seconds to 60 mph or 100-plus mph in the -mile it can't be called a slouch. But there are caveats here, notably that the S6 makes more torque than the M5, at half the engine speed; you have to push a button (or more) on the M5 to engage the 500 hp (it's 400 default) and reaction and harshness are increased with it; and both the M5 and E63 are rear-drive only. This pleases enthusiasts especially when electronic chassis controls can be dialed back, but in real-world driving the S6 puts on a quite respectable showing and in the rain or snow it would be no contest. The S6 is also a bit easier on gas and costs at least $10,000 less than the other two.

Newton would like the S6 as it's good at all the opposite reactions as well. The brakes are so big the number of caliper pistons becomes irrelevant, the S6 stopping quickly even if you're using all 435 ponies downhill between hairpins, and the pedal is solid and progressive as it should be so your passengers don't become bobble-heads in traffic. The quattro all-wheel drive system runs nominally with 60 percent output to the rear axle to bring balance closer to neutral the nose-heavy S6 will understeer at the limit which is no bad thing surrounded by Californians, and with sticky 265/35ZR19 tires on 9-inch wide wheels the S6 claws its way out of a corner better than anything short of rally cars like the Subaru WRX STi or Mitsubishi Evolution.

Naturally the suspension has been upgraded as well, possessing firmer springs, shock settings and bushings than those found in the closest A6 sibling, the S-line. The ride is firm and forgiving as it handles everything from lane divider dots to big dips with aplomb but no imperfection will go unnoticed; this is communication rather than annoyance, and only passengers indulging in leather heated seats and expecting a limo might profess a wish for something softer. A lap or two should convince them otherwise.

It's a wonderfully inviting and invigorating sedan from the driver's seat, with an exhaust note that splits the difference between a thrumming V-10 and a haunting echo. Steering requires just the right effort; it's a near silent cruiser with minimal road noise and the slick aerodynamics all but eliminating wind noise at double-digit speeds, and the shift paddles bring excellent response for an automatic transmission. It's one of those cars that encourage you to go for a long ride, not a weekend afternoon cruise.

Visual cues are typically restrained, with an S6 badge in the grille and V10 logos on the front fenders, four exhaust outlets at the rear corners, deeper front air dam and larger grille openings, aluminum-finish mirrors and a near indistinguishable rear spoiler. The wheels are called "wing" style although the profile of the spokes suggests "propeller" might be a more apt descriptor, and the LED daytime running lights lining the lower edge of the headlight units show everyone from Sweden to Japan how they should be done.

In the cabin, sport seats rule. They're a match for any other sport sedan for adjustability and comfort, and include heaters, small bins under the front, driver memory, and high-grade nappa leather; rear seat occupants are nearly as well coddled (heaters are optional) and get more legroom than the M5 or E63. Recent years have seen Audi presented many awards for interiors and this is no exception as it's well finished and functional. Gray birch is the standard tree trim though carbon fiber can be substituted and either gives a sophisticated, business like appearance if not the warmth of a more traditional luxury interior.

Beyond a suitably thick and curved steering wheel (upshift right paddle, downshift left, rotary wheels for your thumb to control cruise and audio) sit a 190-mph speedometer and 7,000-rpm redline tachometer framing the trip/temp display. The seven-inch navigation screen is up high in the center of the dash and angled to the driver for easiest viewing, and operated by the MMI (multimedia interface) controller and 12 adjacent buttons on the console which is far from the most difficult to use, but not the easiest either. Engine and brake controls surround the shifter, dual-zone climate control is ahead of it, and two handy buttons next to the nav screen turn the screen off and open the glovebox. Ambient lighting in the footwells, roof and recessed space behind the door trim strips are LEDs.

If you checked every option box bits like custom paint, voice recognition navigation with parking assist, window shades, solar sunroof, adaptive cruise control, etcetera you might get an S6 up to $84,000, still less than the base price on an M5 or E63; when two major car mags did the S6/M5/E63 test, the Audi ranked first in one and second in the other for the highest average finishing position.

And neither of those tests was done in inclement weather.

(Whale, a longtime Ventura County resident, has been breaking parts for 29 years and writing about it for 21.)

2007 Audi S6

Engine: 5.2-liter DOHC V-10, 435 bhp

Length/width/height (in.): 193.5/79.2/57.2

Weight: 4,486 lbs.

MPG city/hwy/observed: 15/21/17.5

Base warranty: 4 yrs/50,000 miles

Price as tested: $79,070

Alternatives: BMW M5, Cadillac STS-v, Jaguar XJR, Mercedes-Benz E63