Peugeot trip computer overestimates fuel efficiency.

Two years ago, I suspected that the fuel efficiency that my car’s trip computer calculates was leaner than the actual consumption. Two years and 50,000 kilometers later, this appears to be the case. On average, the trip computer states the car uses 0.75 fewer liters of fuel per 100 km than the actual consumption. That’s about 5 miles per gallon in American units. For whomever cares, the car averages 6.3 liters per 100 km, or 37 mpg, and drags a family of 3.4 people around town and on moderate, occasional road trips.

Figure 1. Actual fuel consumption (blue) vs. stated fuel consumption (pink).