Petrol prices vary by as much as 45 cents between stations across Melbourne, with some selling fuel for as high 171.9 cents per litre, as Victorian families prepare for the first week of school holidays.

Fuel prices at some service stations are at their highest since October 2018.

In South Melbourne, fuel price website Petrolspy lists seven petrol stations, all showing prices of more that 165 cents per litre.

But less than four kilometres away, a cluster of petrol stations in Port Melbourne is selling the same product for 129 cents per litre. The fuel prices are uploaded by members of the public and are regularly updated.