Tamaulipas → San Luis Potosí · Autopista 40D Reynosa-Monterrey
Before turning the key for San Luis Potosí, San Luis Potosí, out of Reynosa, Tamaulipas, run through the pre-trip checklist: registration card in the glovebox, current insurance card on your phone, working SunPass or E-ZPass transponder for the electronic toll plazas along Autopista 40D Reynosa-Monterrey, and a printed backup of the destination address in case GPS reception drops. The locked itinerary measures 646 km (401 miles) with an optimistic estimate of 7h 11m if cruise control sits steadily within the posted limit. Pulling out of Reynosa, the frontera con McAllen y polo maquilador del noreste fronterizo, the road eventually delivers you to San Luis Potosí, the capital potosina y nodo logístico que conecta el Bajío con el norte del país. Schedule departure outside the morning rush window and pack a thermos of coffee to skip an unscheduled stop in the first hundred miles. Budget around MXN 1301.96 just for the pump (53.8 liters / 14.2 gallons of gasolina Magna) plus headroom for tolls. Outbound reimbursement at MXN 6.50/km equals MXN 4199.00 cleared to the driver. Use the Clara generator the moment you park to wrap everything into a single digitally signed PDF. For the US professional driving the 646 km (401 mi) between Reynosa and San Luis Potosí, reimbursement of MXN 4199.00 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 Reynosa→San Luis Potosí corridor must show date, business purpose, and odometer readings.