If you manage a fleet, you've seen at least three alternative fuel cost comparison spreadsheets in the last year — most from vendors who left out the infrastructure line item. I'm Patricia Delgado, a fleet operations manager in Dallas, and I've spent two decades in this seat. Here's what I tell other managers: the true cost of any fuel isn't the gallon price or the kilowatt-hour rate. It's the fully loaded cost per mile, including downtime, driver training, and the maintenance surprises that show up 40,000 miles in.
Why Most Alternative Fuel Cost Comparisons Are Useless
Most alt-fuel comparisons that cross your desk start with a fuel price chart and end with a grant application. They don't tell you what it costs to put a truck on the road. I've sat through vendor presentations where electric looked like free money — then I asked about the 277-volt charging install and the transformer waitlist, and the room went quiet.
A useful comparison has to include fuel price, the vehicle's energy consumption, infrastructure cost spread over the asset's life, the maintenance delta, and five-year resale value. Add the regulatory layer — CARB, EPA, FMCSA — and you have a working model. That's the spreadsheet I run. The rest is marketing.
The Per-Mile Numbers I Actually Track
Here is the starting point for a real alternative fuel cost comparison: a medium-duty truck running diesel at 7 mpg and $3.80 per gallon costs about $0.54 per mile in fuel. The same truck on CNG at $2.80 per diesel-gallon-equivalent and 6 mpg-equivalent comes to roughly $0.47 per mile. Propane autogas at $2.50 per gallon and 6 mpg lands near $0.42 per mile.
Electric is where the range gets wide. A Class 6 box truck pulling 0.9 to 1.2 kWh per mile at a depot rate of $0.25 per kWh costs $0.23 to $0.30 per mile. Charge at a public DC fast charger at $0.45 per kWh, though, and that climbs toward $0.50, wiping out most of the fuel savings.
From our fleet's data, route profile matters more than sticker efficiency. A delivery route with 60 stops an hour gets half the efficiency of a highway run, and stop-and-go traffic plus hot Texas summers drag the battery harder. Diesel pays its own idle tax: air conditioning at a dock burns roughly a gallon an hour.
Fleet Impact: fuel is typically only 30% to 40% of operating cost per mile. Depreciation, maintenance, and driver wages dominate the total cost of ownership. Don't let a fuel-price chart make the decision for you.
Where the Comparison Gets Complicated
That is a sensible alternative fuel cost comparison for fuel alone. The complication is everything around the fuel. A private CNG station runs $1 million or more to build, with permitting that can stretch past a year. Propane needs tank installation, fueling training, and fire-code inspections in some jurisdictions. Electric demands charging infrastructure, panel upgrades, and utility capacity — in parts of Texas, the transformer lead time alone is running six to nine months.
Then there's range. A diesel truck can tank up in 10 minutes and run 600 miles. A battery-electric truck in a real route profile might need two charging stops on a long day, each one eating scheduled driver hours. If your routes are local, that doesn't matter. If you run 400-mile line-haul legs, it changes everything.
Depreciation is the part my CFO hates most. Early electric trucks have taken a beating in resale because the tech is moving fast and buyers worry about battery health. Lease companies price that risk in, so your monthly payment stays higher even though fuel is cheaper.
The DOT and FMCSA Angle Most Spreadsheets Miss
Regulation is where many alt-fuel plans stall. In California, CARB's Advanced Clean Fleets rules already force zero-emission purchases for certain fleets, and a growing list of states follows the same playbook. That matters even if you sit in Texas, because a load into California can trigger reporting requirements.
On the FMCSA side, electric vehicles change maintenance and inspection practices. High-voltage systems mean your shop needs trained techs, insulated tools, and new safety procedures. Propane and CNG vehicles have their own fueling and parking rules under DOT hazmat-adjacent guidance.
Fuel pricing adds another variable. Propane tracks heating fuel markets, and CNG follows natural gas swings. A long-term contract can smooth the curve, but it ties you to a station you may not control. None of this appears on a fuel price chart, but it lands in your budget within the first year.
How to Run Your Own Alternative Fuel Cost Comparison in Four Steps
Build your own model. Step one: pull 12 months of route data and calculate average daily miles per vehicle. Step two: quote the actual vehicles you'd spec, not the brochure trim. Step three: price infrastructure at your site, including transformer wait, station build, and lost parking spaces. Step four: add a five-year total cost of ownership line for depreciation and maintenance.
One thing that will anchor your alternative fuel cost comparison in reality: run a pilot. I've watched a single electric box truck on one fixed route for six months reveal more useful numbers than any spreadsheet. The pilot shows the real kWh per mile in your traffic, the real downtime for charging, and the real driver reaction — three things no vendor deck will ever predict.
Bottom Line
The best alternative fuel cost comparison is the one you run on your own routes with your own drivers and your own electricity bill. Diesel still wins on simplicity. Electric wins on cost per mile when you control the charging. CNG and propane sit in the middle for high-mileage hometown routes. What it costs, what it pays back, what it triggers with DOT — that's the whole job. Run the numbers clean, and the right answer for your fleet shows up in plain sight.