It’s our destination as we test a posh Mercedes-Benz SL350 SUV, complete with all the technological advances in transportation for the 21st century.

Back in 1919, this rail line opened to great fanfare, completed with by the checkbook of John D. Spreckels and hundreds of laborers who worked through extreme heat and cold in a landscape that was later used to train moon astronauts. We’re using a narrow trail through the desert to reach it from county Highway S-2, the Great Overland Stage Route of 1819, which celebrates an earlier form of getting from here to there. It’s also the route of Juan Bautista de Anza, the Spanish conquistador who blazed the inland trail from Mexico to California.

For today’s visitors, this end of the desert is usually quieter but offers the same amazing vistas as the busier northern end, near the town of Borrego Springs. The trail is mostly packed sand, with a few small hills where the road is marked with shallow ruts and a few rocks. It’s a road that any SUV with high ground clearance and all-wheel-drive should be able to take.

The metalic silver ML350 tested is equipped with the 4matic all-wheel-drive system, air supsension that lifts it a few inches, downhill engine-braking that kicks in under four miles an hour on downgrades, and enough exterior sensors to let drivers know when there’s something too close… it seemed really scared of ocotillo, the tall, spindly plants that enjoy this area. It’s nice for this road; not too wide that you’re going to put Arizona pinstripes (scratches from plants) into your beautiful basecoat-clearcoat paint.

For most of the trail, everything was fine, until about a quarter-mile from the station. Among the items monitored by the truck is the tire pressure, and things started beeping about the same time the water tower was in sight. The rear tire on the driver’s side was losing pressure. The driver’s display turned red, giving me readouts of the tires. Three were all about 40 psi, but that left rear was dropping a few pounds at a time.

It was over the last ridge and the tire was down to about 15 pounds, but the ML made it to the hard-packed sand beside the tracks with enough air in the tire to keep from destroying the rim. Fortunately, the ML has a spare – even though it’s a space-saver doughnut, it was up to the trip back over the rough road and the freeway back to San Diego. I also thank the assembly workers in Alabama that put together this luxo-ute, as they didn’t overtighten the lug nuts. I remembered just enough from the last time I changed a tire – probably 30 years ago – to get the new tire installed.

A couple of folks in apparently tougher vehicles came by while I was changing the tire and offered help, but I was just fine. I was also visited by a park ranger (so you can find a cop when you need one), but even with Mercedes’ outside temperature reading reaching 90 degrees, I was darned proud of myself when I successfully changed the wheel. I asked the ranger to check back in an hour, or just come by if he saw vultures circling.

Fortunately, I had taken along a couple of bottles of water and an extra sandwich, which came in handy while changing the tire. Always take provisions when visiting the desert; you never know what will happen.

Even with the tire trouble, this is a fairly easy drive and a nice day trip from San Diego. I wouldn’t recommend – and hadn’t planned to try – going over the railroad tracks and heading into the hills. After all, the ML isn’t a full-on 4×4, and there isn’t a ramp over the tracks, just some piled-up concrete chunks that get drivers about the height of the ties. There are still two rails to cross and the other side to drop down, so it wasn’t something that the ML was equipped for.

And the rails are still used, according to the park ranger, so keep an eye out for trains. A company called Carrizo Gorge Railway operates freight trains through the area. Passenger service was spectacular, especially as the route crosses over the famous Goat Canyon Trestle, numerous other bridges and tunnels in a circuitous route from here to Campo, then over the border from there, through Tecate and reentering the US at the San Ysidro border crossing.

In those days, the San Diego and Arizona Eastern Railroad offered through sleeping cars on routes with romantic names like the Golden State Limited or the Sunset Limited. The old Southern Pacific ran the line for most of its history, even putting out brochures during World War II inviting servicemen to take the route back home.

The railroad was completed in 1919 and it must have really been something to stop for water here and see visitors to California from the east crunch around in the desert sand for the first time. Sadly, the line stopped hauling people in 1951, ending the days when you could book trip from San Diego to Chicago or New Orleans without going through Los Angeles. Today, Interstate 8 slices through the desert.

A few old postcards, brochures and other relics still remain, but the days of watching the desert go by from the comfort of your Pullman car are long gone.

Back in the 21st century, my technologically advanced SUV was now on four tires again and ready for the trip out. The donut tire made it out and the rocks weren’t that bad. I vote for a defective tire mount or something. It was comforting to have the system telling me how fast the air was escaping, so I could hurry a bit to the packed sand.

When you visit, I hope your day doesn’t include a tire change. Bring a lunch; it’s a beautiful view from there.