In terms of fuel efficiency, there shouldn't be a significant difference between the Harley-Davidson 1200 Sportster Custom and the Harley-Davidson 1200 Sportster 72, as both models are powered by the same engine.
The Sportster Custom and the Sportster 72 share the same engine, which is a 1200cc Evolution V-twin engine. This engine is known for its relatively similar fuel consumption across various Sportster models.
Actual fuel economy can vary based on several factors such as riding style, road conditions, maintenance, and individual bike modifications. Additionally, differences in weight and aerodynamics between the two models could potentially result in slight variations in fuel efficiency, but these differences are likely to be minimal.
It's always a good idea to consult the specific manufacturer's specifications or reach out to a Harley-Davidson dealership for the most accurate information on fuel efficiency for each particular model.