They are not the same kind of thing
A fuel card is a payment and control instrument. It lets drivers buy fuel at other people’s pumps, on your account, with rules about where, when and how much. It does not move any fuel.
On-site fueling is a supply arrangement. A tanker comes to where your vehicles are parked, usually overnight, and fills them. Nobody goes anywhere to buy fuel.
Comparing their per-gallon rates misses the point. One is a way of paying for retail fuel; the other removes the retail trip.
The cost that appears on neither invoice
The fuel-card discount is visible and easy to compare. The cost of the fueling trip is neither, which is why it is usually left out of the comparison entirely.
A fuel stop is rarely just the minutes at the pump. It is the detour off route, the wait if the diesel lanes are busy, the receipt, and the reconciliation afterwards. Estimates of what that costs vary enormously by operation, so the only number worth using is your own.
Work it out directly: take one driver, follow one week, and count the minutes actually spent acquiring fuel rather than driving. Multiply by your fully loaded hourly cost, then by the fleet. Most operations have never done this, and the result is usually larger than the discount being argued over.
Where fuel cards genuinely win
There are fleets for which a card is simply the right answer, and it is worth saying so:
- Long-haul and dispersed routes.If the vehicle does not reliably come back to a yard, there is nowhere for a tanker to meet it. A card follows the truck; a tanker cannot.
- Small or highly variable fleets.A handful of vehicles with unpredictable patterns rarely justifies a scheduled delivery.
- No space for a tanker.On-site fueling needs a yard a tanker can work in safely. Some sites simply do not have one.
- Mixed purchases on the road.Drivers buying gasoline, DEF and incidentals get a single account and one control system for all of it.
Where on-site fueling wins
The pattern is consistent, and it turns on geography more than size:
- The vehicles return to a yard.If the fleet sleeps in one place, fueling it there removes the trip entirely. This is the single biggest determinant.
- Driver hours are the constraint.Where hours-of-service limits or overtime govern what you can deliver, time recovered from fuel stops becomes time available for work.
- Equipment that cannot drive to a pump.Excavators, generators, reefer units and site plant have to be fueled where they stand regardless.
- You need usage data, not purchase data.A card tells you what was bought. On-site delivery with tank monitoring tells you what was consumed, by which vehicle, and when.
Control: the honest version
Fuel cards are sold on control — spend limits, product restrictions, purchase alerts, exception reports. Those controls are real, and they exist because retail fueling creates the risks they manage. Card misuse and fuel slippage are well-documented problems, and the card is the tool built for containing them.
On-site fueling reaches the same place by a different route: the fuel goes into your vehicles from your supplier’s truck, metered per vehicle, with no purchase transaction to misuse. That is not better control so much as less to control.
Plenty of fleets run both — cards for the road, on-site for the yard — and any supplier worth talking to will tell you when that is the right answer.
What to actually compare
If you are weighing the two, these are the questions that decide it:
- What share of the fleet returns to a yard nightly?Above roughly half, on-site fueling is worth pricing properly.
- What is a driver hour worth, fully loaded?Not the wage — the wage plus everything else, plus the work that hour could have produced.
- How many minutes a week go to fueling?Measured, not estimated. The whole comparison turns on this number.
- What does the card actually cost?Transaction fees, monthly fees, and the real spread on the headline discount once network restrictions are applied.
- What will you need to report?If per-vehicle consumption or emissions reporting is coming, purchase records will not produce it.
Our position, stated plainly
Summa delivers fuel and does not issue fuel cards, so read this as an interested party being straight with you rather than a neutral one.
Our view is that the comparison is settled by geography and driver hours rather than by price per gallon — and that a dispersed fleet with no home yard should use a card, because on-site fueling cannot serve it well and we would tell you that on the phone.
If your vehicles do come back to a yard, give us the count, the location and roughly what you burn. We will tell you what on-site fueling would cost and what it would save, including if the answer is that it would not be worth it.