In September 2018, fuel in Belgium averaged €1.449 for petrol

Petrol, monthly average€1.449/L
Diesel, monthly average€1.491/L
LPG, monthly average€0.630/L
Weekly bulletins held for September 20184

Monthly averages for Belgium across September 2018, from the stored EU Weekly Oil Bulletin monthly history (European Commission, CC BY 4.0).