Cutting Through Unexpected Urban Wilderness In A Hybrid Mercury Mariner

While the general area where San Diego, Orange and Riverside counties meet is one of fastest growing in the nation, its center somewhat of a surprise.

Much of it is wilderness.

This hole-in-the-donut is the northern portion of the Cleveland National Forest, which stretches south to near the US-Mexico border and is familiar to most San Diegans as the home of Mount Laguna and Mount Palomar.

For drivers of the scary Ortega Highway, the area on today’s drive is the highest part of the road from San Juan Capistrano to Lake Elsinore. Campgrounds and picnic areas, hiking trails and off-highway vehicle areas are along this stretch of state Route 74.

A topographic map will show hills, canyons and mountains that seem to be linked all the way from the seaside cliffs of San Clemente and San Onofre all the way to Fallbrook, Mount Palomar and beyond. Freeway drivers pass by and through these mountains all the time. On Interstate 5, they rise quickly east through Camp Pendleton and San Clemente, while on I-15, the freeway cuts majestically between the peaks.

Creek-crossing in the Cleveland National Forest.
Creek-crossing in the Cleveland National Forest.

The rugged terrain is a big reason there are no east-west freeways between SR-78 in San Diego County and SR-91, which crosses from Orange to Riverside counties. In between is the notorious Ortega Highway, a twisty, narrow, two-lane road that at times has extremely heavy traffic.

This open space has left a welcome hole in the region’s sprawl that’s perfect for off-road exploration. Except it’s not really off-road, since most of today’s route from South Main Divide to Los Alamos Road is paved. But since I had an SUV and the folks at Ford had challenged me to do a little “green” off-roading with a hybrid, all-wheel-drive Mercury Mariner, I did check out the first dirt trail I found, but more about that later.

To get there, it’s a straight shot up I-15, exiting at SR-74 west in Lake Elsinore. A few zigzags through town and a few more on the quickly rising cliffside highway and drivers reach the summit, elevation 2,666 feet. Just past is the sign for the Main Divide (north and south); we head south today, skirting the San Mateo Canyon Wilderness and the Wildomar Off Highway Vehicle Area. The El Cariso Visitor Center (951-678-3700)is located on Ortega Highway just west of where we leave SR-74.

This is one spectacular byway. Turn left off of Ortega Highway to South Main Divide Road, passing the Wildland Firefighter Memorial Picnic Area and one of the many Penny Pines forests in California.

On the trail in a hybrid Mercury Mariner.
On the trail in a hybrid Mercury Mariner.

For a few miles, this is a fine road, wide and paved. It narrows after passing old Rancho Capistrano about four miles south. Good enough, in fact, that I might even return sometime in the Miata.

Still shown on some maps and signs as Killen Trail, it was changed back to South Main Grade in 2003. The street became notable in 2002 after hikers found the body of 5-year-old Samantha Runnion near the road.

The vistas here are spectacular as the road snakes from one side of the divide to the other. At one moment, drivers are looking east at the 1,500-foot drop to Lake Elsinore; hang gliders sometimes launch from this area. After the next curve, the road overlooks an unspoiled coastal canyon.

Rancho Capistrano is a small island of homes in the middle of the National Forest about four miles from Ortega Highway; beyond the road narrows, but is still paved and generally begins to descend.

Mountain vista south of SR-74 in the mountains of Orange County.
Mountain vista south of SR-74 in the mountains of Orange County.

About eight miles in, a dirt road snakes off to the left. Called Calle Campanero at the bottom, some maps identify it as the end of South Main Divide Road. It’s a quick drop to the estate homes in the valley below; twisty, rocky and rutted, cut into the cliff in many spots. In short, lots of fun.

It was here I really noticed I was driving a hybrid. Not traveling much above 20 miles per hour because of the terrain, I glanced at the tachometer and… it read zero. Mr. Gasoline Engine was taking a nap. But the brakes, power steering, CD player and everything else was running. A quick glance at the small video “information center” in the center of the dash showed the fuel economy was off the scale — because no gas was being used.

On the rare occasions when the road climbed slightly, the electric motor pushed the Mariner a bit, then the gas engine would kick in smoothly. No problems here.

At the bottom, I decided to just make a u-turn and head back up the trail. On the way back up (an elevation rise of at least 500 feet over two miles, I’d guess), Mr. Gas was needed the whole way. And the Mariner’s all-wheel-drive system was up to the task, rolling up, down and through the rocks and ruts just fine.

It didn’t seem quite as sure as the Jeep Liberty I took up the rocky road southeast of Mt. Laguna last year, but the Mariner isn’t advertised as having conquered the Rubicon. For an SUV that would probably spend most of its life as a grocery-getter and commuter, it’s got a real fun side. Not to mention, when the motor shuts off, you’re not polluting this natural area.

A two-wheel-drive SUV would be fine on all but the dirt segment, so this drive would be open to my neighbors and their hybrid Ford Escape, the Mariner’s corporate twin.

Back at the top of the hill, I continued south on the paved road, now a bit narrower. Maps seem to indicate this is called Los Alamos Truck Trail or Los Alamos Road, but I wasn’t able to get a definitive answer. Whatever it is, I just continued south, passing the entry to the Wildomar Off Highway Vehicle Area.

From there, the road kept descending, reaching the bottom of Los Alamos Canyon. There, it parallels, then crosses, Los Alamos Creek. The crossing was dry when I visited just before Thanksgiving, but if we’ve had some rain, it might have a lot of water flowing very fast, as the bottom of the canyon is narrow. The concrete road doesn’t bridge the creek, it just goes through it. So, when there’s water the road will be wet, take care.

A few more twists and climbs and you’re back on Cleveland Forest Road, cruising again through the estate homes. It’s been about 20 miles since exiting Ortega Highway (excluding the four-mile dirt trek) and another 15 miles on regular country roads to I-15.

This area is the donut hole of nature in the middle of urban Southern California and well worth exploring. And if your vehicle is green, go ahead and check out nature guilt-free.

Route and Info

  • From November 2006


  • Easy to moderate on South Main Divide-Los Alamos Road.
  • Difficult on dirt road South Main Divide-Calle Campanero.


  • About 46 miles from I-15 at Central Avenue in Lake Elsinore to I-15 and Clinton Keith Road in Murietta. Central Avenue exit off I-15 is about 80 miles from downtown San Diego. Additional 8 mile round-trip dirt segment.


From central San Diego
  • Interstate 15 north to Lake Elsinore.
  • Exit at Central Avenue SR-74. Go west (left) and follow SR-74 west signs.
  • Right at Collier Avenue. — Left at Riverside Drive.
  • Bear left to continue onto Grand Avenue.
  • Right at Ortega Highway.
  • Left at South Main Divide.
  • For dirt segment, follow South Main Divide about 8 miles after leaving Ortega Highway.
  • To return to I-15, follow Calle de Campanero, right at Avenida La Cresta, left at Tenaja Road, left at Via Volcano to stay on Tenaja Road, continue onto Clinton Keith Road to I-15.
  • At dirt road about eight miles in, road changes name to Los Alamos Road, later Tenaja Truck Trail, then Cleveland Forest Road.
  • Left at Tenaja Road.
  • Left at Via Volcano to stay on Tenaja Road.
  • Continue onto Clinton Keith Road to I-15.

Mercury Mariner Hybrid video review


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