The 2014 Audi RS 5, which is practically unchanged from the 2013 version (pictured), is a well-engineered, brilliantly thought-out car that begs to be driven. (AUDI /AUDI )

Driving the Audi RS5 Quattro coupe is like being in a forbidden relationship. You know you shouldn’t be doing what you’re doing. But it feels so very good doing it, you don’t want to stop. You know you’re going to pay for what you’ve done.

I paid — $110 in premium gasoline for nearly 300 miles of unadulterated fun. I am lucky I didn’t pay significantly more. I did most of my driving on the highways and byways of the great state of Virginia over the Fourth of July weekend. I was careful. But luck in any passionate activity is often more important than care.

I was lucky. I finished the drive with no traffic tickets or warnings and, more important, no crashes or other mishaps.

There are stretches of Interstate 66, moving west toward Virginia’s Shenandoah Valley, with top legal speeds of 70 mph. Sometimes it pays to be the wimp in the company of fools. I was going 80 mph — easily achieved in an all-wheel-drive car powered by a 4.2-liter V-8 gasoline engine (450 horsepower, 317 pound-feet of torque).

I wasn’t trying to show off. Instead, I was trying to stay out of the way of apparently crazy drivers moving substantially faster and, happily in terms of reduced official attention to me, into the waiting arms of the law.

There are some side roads in central Virginia, mostly traffic-free pavement moving toward West Virginia, that are as tempting to drivers of high-performance automobiles as that forbidden apple must have been to Adam and Eve in the Garden of Eden. I chose several of those roads, my passion for them tempered by biblical recollections of what happened to Adam and Eve after they ate that apple.

But the temptation was too much to resist. Blame it on brilliant automotive technology coupled with the rare on-road opportunity to try it out.

Some of those side roads have marvelous twists and turns, perfect for trying out the RS5 coupe’s standard offering of a sport rear differential that keeps the outside rear wheel turning while the inside rear wheel is braked, allowing the car to make sharp turns with little or no drama. This was fun. I ran that exercise multiple times just to make sure the car was doing what Audi’s engineers said it would do. At least, that is what I told myself. It’s amazing how the mind works in justification of the unjustifiable.

Truth is, I was having a devilishly good time, a motorized revelry that sometimes bordered on the silly and, had it been in a less rural setting, the annoying. I am referring to the RS5 coupe’s deep baritone exhaust note escaping from its dual exhaust outlets each time I mashed the accelerator in an attempt to move from 0 to 60 mph in under 5 seconds. My best time was 0 to 60 in 4.4.

That dubious achievement left me feeling proud and ashamed. As many visitors to this space know, I normally don’t care about such things. Indeed, I often frown on them, as I do on those television commercials featuring cars speeding along usually empty roads with demonic fervor.

I now know what it feels like to be a publicly religious “family values” politician caught camped in the diggings of a paramour. “I knew that woman. It was a moment of inexcusable weakness. I apologize to my wife, my children, my staff and my constituents. I will seek rehabilitation . . . ”

Short of that. I will at least enter a season of abstinence devoted to motoring in very fuel-efficient (of which the RS5 coupe definitely is not one), reasonably affordable (only for the top 1 percent of the nation’s income earners in the case of the RS5), and practical (the RS5, a genuine daily driver, actually deserves some credit here) automobiles.

My visit to the dark side is now ended. I now know how difficult, if not impossible, it will be to save the rest of the fallen. That place is fun.

Nuts & Bolts
Audi RS5 coupe

Bottom line: The Audi RS5 coupe is an amazingly beautiful automobile — to look at, to sit in and to drive. Fully equipped at nearly $80,000, it is a car for the precious few. But it’s nobody’s bauble. It is every inch a well-engineered, brilliantly thought-out car that begs to be driven.

Ride, acceleration and handling: It gets top marks in all three.

Body style/layout: The Audi RS5 is a front-engine, all-wheel-drive luxury model available as a two-door coupe (driven for this column) or convertible. It shares a platform with the Audi A5 and S5 sedans. For this column, I drove the 2014 model, which is practically unchanged from the 2013 version first sold in the United States, and which will be similar to the 2015 car.

Head-turning quotient: It has a stately exterior with a hint of aggression. The interior — a work of carbon-fiber accents and well-stitched Napa leather—is unmatched by anything in its class.

Engine/transmission: The Audi RS5 Quattro coupe comes standard with a 4.2-liter, 32-valve V-8 gasoline engine with variable valve timing linked to a seven-speed automatic transmission that also can be operated manually.

Capacities: Seating is for four people, with the rear seats best reserved for shorter folks. Cargo capacity with all seats in place is 12.4 cubic feet. The fuel tank holds 16.1 gallons — premium grade is required.

Mileage: Under perfect road conditions, you get 16 miles per gallon in the city and 23 on the highway. Road conditions are very seldom perfect, which means you usually get less in this one.

Safety: Standard equipment includes front and rear ventilated disc brakes, four-wheel anti-lock brake protection, emergency braking assistance, electronic brake-force distribution and electronic stability control.

Recommended optional safety features: Get the MMI Navigation Plus package, which includes onboard navigation, rearview backup camera, and blind-side monitoring and lane-departure warning systems.

Price: The base price on the tested 2014 RS5 Quattro coupe is $69,600, with a dealer’s invoice price of $64,728. Price as tested is $80,390, including $9,895 in options (onboard navigation with rear backup camera, advanced electronic safety equipment, optional 20-inch diameter wheels and other items).