* Year of the van: Older vehicles generally have worse gas mileage than newer ones due to less efficient engine technology.
* Condition of the engine and vehicle: A well-maintained engine will get better mileage than a poorly maintained one. Things like tire pressure, proper alignment, and aerodynamic factors all play a role.
* Driving habits: Aggressive acceleration and braking significantly reduce fuel economy.
* Vehicle weight: A heavily loaded van will get worse gas mileage than an empty one.
* Transmission type: Automatic transmissions tend to be less fuel-efficient than manuals.
* Rear axle ratio: A higher numerical ratio will improve acceleration but reduce gas mileage on the highway.
You'll likely find widely varying reports online. To get a reasonable estimate, you'd need to specify the year of the van and look for specific fuel economy data for that exact model and year. Even then, expect some variance based on the other factors listed above. Expect gas mileage to be relatively low compared to modern vehicles; likely in the 8-15 mpg range, but possibly lower depending on the factors mentioned above.
