Vehicle-Fleet´s Managers require to identify relevant aggregate metrics to monitor the performance of their vehicles and drivers. The chosen metric should help in the decision making process of programs relative to the vehicle maintenance, drivers awarding, vehicle routing, fleet renovation, among others. It is well known that fuel consumption is around half of the operative cost of vehicular fleets. However, fuel consumption depends of several factors, such as, vehicle weight, load, route, vehicle technology, road conditions, driving patterns, traffic, among others. Therefore fuel consumption by itself is not an appropriate metric for these purposes. The situation worsen for the case of freight transportation where companies usually have a large diversity of vehicles capacities and technologies and cover many different routes.

We hypothesized that specific fuel consumption, measured as l/km-gross ton, is the metric to follow. To test this hypothesis, a monitoring campaign was developed on a non-homogenous fleet of 50 heavy-duty freight vehicles, with nationwide operation, in a country with large variations in altitude (0-3500 masl), during two months of normal operation.  Fuel consumption behavior was analyzed with several options of performance metrics. Results indicated that for cases when vehicles are almost always fully loaded, specific consumption measured in [l/km – curb ton] also works for these purposes.