The Low-Fuel Light Is a Warning, Not a Countdown
Treat the low-fuel light as a prompt to fill up at the next station, not as a reserve you can spend. The amount of usable fuel left when it comes on is set by the manufacturer and differs from car to car, and the trip computer's miles-to-empty figure is an estimate built from how you have been driving recently — not a promise about the driving you are about to do.
That gap is where people get caught. The US Department of Energy notes that gas mileage "usually decreases rapidly at speeds above 50 mph" and that aggressive driving "can lower your gas mileage by roughly 15% to 30% at highway speeds and 10% to 40% in stop-and-go traffic." A reserve calculated while you crawled down State Street at 25 mph will not stretch as far once you are running 75 up I-15 toward the Point of the Mountain.
Two Sandy-specific habits make it worse. The first is the climb: everything east of Wasatch Boulevard gains elevation quickly, and an engine working against a sustained grade burns fuel faster than the same engine on the flat. The second is waiting. Idling alone "can use a quarter to a half gallon of fuel per hour," so twenty minutes stuck behind a ski-traffic backup on a winter morning is fuel you had budgeted for the drive home.
Where You Stop Matters More Than When
Pick your stopping place while the engine is still running, because once it dies you have only the momentum you already had. A car that runs dry does not stop instantly — it surges, loses power under load, and gives you a few seconds of coasting. Spend those seconds moving right and getting as far off the pavement as the shoulder allows, not on the hazard lights.
On I-15 through Sandy, aim for the right shoulder and keep going until the car is fully clear of the white line, past an exit gore if you can reach one. The left shoulder is worse in every way: traffic passes closer, there is less room to stand, and anyone coming to help has to work with their back to the fast lane. On surface streets like State Street or 9000 South, a parking lot entrance or a side street beats the curb lane, and is worth steering for even if the last hundred feet are uphill.
The canyons change the calculation completely. UDOT's own guidance for the Cottonwood Canyons is blunt: "SR-190 & SR-210 are dead-end roads in the winter. Make sure you have all you need!" There is no fuel up either canyon, the shoulders are narrow, and a car stopped on a blind bend in Little Cottonwood is a hazard rather than an inconvenience. If your gauge is low at the mouth of the canyon, fill up in the valley before you start the climb.