San Luis Potosí → Zacatecas · Autopista 57D México-San Luis Potosí
On heavy-rain or dense-fog days the San Luis Potosí, San Luis Potosí, to Zacatecas, Zacatecas, leg routinely demands well more than the 2h 28m estimated: Autopista 57D México-San Luis Potosí carries known hydroplaning hot spots and reduced-visibility corridors that justify dropping to 35 mph through a few short stretches. The outbound run covers 222 km (138 miles) over varied topography between San Luis Potosí (the capital potosina y nodo logístico que conecta el Bajío con el norte del país) and Zacatecas (the capital zacatecana y patrimonio minero colonial reconocido por la UNESCO), demanding sharper attention on mountain descents and shoulder-less curves. Before pulling out, check brake-pad wear, tire tread depth, and washer-fluid level in the reservoir. Fuel spend holds near MXN 447.70 for the 18.5 liters (4.9 gallons) consumed. Even in adverse conditions, the flat tariff of MXN 6.50/km guarantees the standard outbound payout of MXN 1443.00 — log any incidental costs (extra toll, mandatory meal, emergency lodging) in a separate field on the Clara receipt. For the US professional driving the 222 km (138 mi) between San Luis Potosí and Zacatecas, reimbursement of MXN 1443.00 stays non-taxable to the employee when the employer follows an accountable plan under Treas. Reg. §1.62-2 and reimburses at or below the IRS standard mileage rate. US employers generally reimburse at the IRS standard mileage rate so the payment stays non-taxable to the employee under Pub. 463. Keep the IRS-compliant expense report (Form 1040 Schedule C, line 9) alongside the fuel receipt from any EIA-tracked retail station network pump used along the leg; Internal Revenue Service (IRS) examiners pull contemporaneous mileage logs first when auditing Schedule C unreimbursed business expenses, and the San Luis Potosí→Zacatecas corridor must show date, business purpose, and odometer readings.