A classic Chevy Nova with its shaker hood up takes a break from cruising Woodward Ave. All photos by Len Katz unless otherwise noted.

There’ll be plenty of thunder in Detroit today, even though the skies are only partly cloudy. The rumbles are coming from the city’s main drag, Woodward Avenue, where as many as 1.5 million people, and tens of thousands of muscle cars, hot rods and exotics stage are out for the annual Woodward Dream Cruise.

On the other side of the Continent, the crowds will be building all over the Monterey Peninsula for a weekend of excitement wrapped around the tony Pebble Beach Concours d’Elegance, considered by classic car fanciers the crowning event of the year.

The Dream Cruise and the Concours highlight two very different aspects of the automotive world – and underscore the fact that America’s love affair with the automobile has hardly diminished. But what’s a gearhead to do – unless you have a private jet ready to whisk you from one to the other?

Confetti flies as the 2013 winner is announced at Pebble Beach Concours. Photo by Paul Eisenstein

Detroit’s gathering is a show for the masses, allowing anyone to participate. If past years offer a hint of what’s to come all day Saturday for the official Woodward Dream Cruise, as thousands of muscle cars, hot rods, sports cars and exotics will spend the day cruising up and down the eight-lane boulevard that serves as the Motor City’s main thoroughfare.

“It gets bigger and bigger every year,” noted regular Dream Cruise fan Bob Wissman, who recalled spending plenty of time riding around with friends in their Corvettes, Camaros and Mustangs as a teenager back in the 1960s.

(Automakers turn to the Woodward Dream Cruise to hawk parts and upgrades. Click Here for more.)

An early Ford Mustang cruising Woodward.

This will mark the 20^th anniversary of an improbable event that took shape almost by accident when a small car club in the Detroit suburb of Ferndale decided to change things up. Rather than having its members park their cars for their annual gathering, organizers thought it would be more fun to cruise up and down Woodward Avenue. Word got out and almost 250,000 people showed up.

The Pontiac GTO is a favorite among Woodward Dream Cruisers.

That’s expected to reach anywhere from 1 million to 1.5 million this year, according to authorities, with upwards of 40,000 to 60,000 cruisers taking over Woodward Avenue. Those vehicles will be an eclectic mix of modern muscle cars, like the new 2016 Chevrolet Camaro, classic ‘60s cruisers, and even some off-the-wall automotive esoterica. Several Hollywood cars, including one of the Monkeymobiles, are expected out for this year’s Cruise.

Jay Leno, shown with his unrestored Duesenberg, is a regular at the Pebble Beach Concours. Photo: Paul Eisenstein

The Pebble Beach Concours itself is a much more elegant affair, organizers inviting only a select group of the world’s most desirable – and expensive – vehicles for display on the greens of the ritzy Pebble Beach golf course. Among the frequent participants are celebrity collectors such as Jay Leno and Jerry Seinfeld, and fashionista Ralph Lauren.

The Sunday event, which began as a way to raise money for local charities, will bring out thousands of collectors and wannabes from around the world. Those lucky enough to be invited to show a car can only hope of going home with a trophy.

As many as 60,000 classics, hot rods and muscle cars will turn out on Woodward Ave.

That’s enough to get some entrants to invest more than $1 million to restore classics that will include rare Bugattis, Duesenbergs and Talbot-Lagos. Long-time judge Ken Gross said a best-of-show winner could see a lavish payoff, the value of a benighted vehicle often jumping by millions of dollars.

(BMW debuts hot M4 GTS at Pebble Beach. Click Here for a closer look.)

An essential ingredient for every cruiser, a pair of fuzzy dice. Photo: Paul Eisenstein

Those who find the Concours a little too rich for their blood have plenty of other options, the Concours spurring nearly a week of events across the Monterey Peninsula. There are secondary car shows, such as the Concorso Italiano which focuses on “La Bella Macchina,” brands like Alfa, Ferrari and Maserati.

The Pebble Beach Concours brings out some of its own cruisers. Photo: Paul Eisenstein

And for those who prefer to see their classics moving, there’s the annual Monterey Motorsports Reunion. Described as a museum springing to life, it brings out race cars from as much as a century ago and turns them loose for three days of racing at the challenging Mazda Raceway Laguna Seca.

There are also nearly a dozen different classic car auctions spread out across the Peninsula, and sponsors expect they could generate as much as $100 million or more in business before they pack up their tents on Monday, marking the unofficial end of the summer car season.

(Lexus rolls out two updated models at Pebble Beach event. Click Here to check out the 2016 LX and GS.)