The squiggle on the map looked interesting; a road that, judging by the tightly-packed contour lines, looped out off Utah Route 12 into some of the wilder parts of the Grand Staircase-Escalante National Monument in southern Utah. But it was the name of the road that caught my attention: Hell's Backbone. How could we not take a road called Hell's Backbone? Mrs MacKenzie, bless her, shrugged and said why not. I brought Porsche Cayenne's ride height setting back up to normal, switched the air suspension to comfort mode, and headed off along the gravel.
This 38-mile road was built in the 1930s and at the time was the only road connecting the town of Boulder with Escalante to the southwest (the two are now connected by the all-weather Route 12). It climbs to over 9000ft, skirting around the northern edge of the vividly-named Box-Death Hollow Wilderness. The highlight is Hell's Backbone Bridge, a 109-ft long, 14-ft wide structure with only vestigial guardrails that spans 1500ft drops either side. Mrs Mackenzie, who doesn't like heights, is very quiet as we drive across. The bridge is 8822 ft up in the mountains, and I hear the blood roaring in my ears as I run around and grab a few photos.
There's a patch of frozen, deeply rutted snow on the road just past the bridge. I stop and jack the Cayenne up to the High 1, then High 2 suspension settings - giving me 10.5 in of ground clearance - to get through without scraping the Porsche's underbelly. A mile or so further on we're stopped by pine trees that have fallen across the road, beaten down by the heavy winter storms. There's no alternative but to turn around and drive the 17.5 miles back to Route 12 and the tarmac. But the views - and that bridge - were worth it.
And going back onto 12 was an unexpected bonus. We'd spent the previous day meandering up from Monument Valley, stopping off to check out the Natural Bridges National Monument, before heading northwest to the Capitol Reef National Park. The roads were quiet and entertaining; the scenery breathtaking.
Among the highlights: Route 261 which took us northwest off Route 163 near Mexican Hat en route to Natural Bridges and ran straight towards what looks like an impenetrable escarpment. As we neared the escarpment I figured the road would jink north and run alongside it. But the display on the Porsche's sat-nav said otherwise. Then I noticed what appeared to be a knot in the trace on the screen. As we got closer, I saw the road - which is gravel - zig-zagged straight up the face of the escarpment, almost winding back on itself in places. We climbed 850ft in 2.3 miles, and the views were spectacular, especially as there are no guardrails to get in the way.
Route 95 from Natural Bridges is one of the world's great roads. Smooth - and at this time of the year, almost empty - it swoops and sweeps, dips and climbs through truly epic landscapes. I had the Cayenne loafing along at 80 or so; it felt quick, quiet and composed through country that challenged the early settlers.
We crossed the Colorado River near Hite, at the north-eastern end of Lake Powell, before turning left at Hanksville and following Route 24, which hugs the Fremont River as it follows the canyons cut into the pale rock of the Capitol Reef National Park. Capitol Reef is one of the lesser-known parks in Utah, and while it can be very hot in summer, at this time of year it's worth a detour.
We'd found the scenery almost overwhelming; surely there couldn't be more. But back on Route 12, it just kept on coming and coming. The road runs along a plateau that narrows to a Hog Back that's barely a road's width in places, with steep, slick-rock drops either side - and no guardrail - just before it descends into the narrow Calf Creek canyon, where it follows the creek, winding between steep rock walls. At the junction of Calf Creek and the Escalante River, the road climbs up and out on to dramatic bare slickrock; from one viewpoint it looks just like a Scalextric track laid out on your living-room floor.
Past Henrieville, Route 12 turns north again, taking you right past the riotous rosy glory of Bryce Canyon. And just when you think there couldn't possibly be anything more to see, it dives down through the brilliantly-hued Red Canyon before you hit Route 89, the road north to Salt Lake City.
I love cars, but not simply as inanimate concoctions of style and technology. I love the freedom they give you to explore; to take you to new places, see new things, meet new people. You see, there's always an interesting road somewhere. And a car - any car; it doesn't have to be the fastest, the latest, or the best looking - allows you follow it.