The fuel efficiency of your LTV can vary greatly depending on things like weather, terrain, and travel speed to name just a few.
On average, you should expect to see between 14 to 18 miles per gallon from both the Mercedes Sprinter chassis (All Unity models, as well as the Serenity) and the Ford Transit chassis (All Wonder models)
Here's a few tips if you want to get the most out of your fuel
Try not to drive too aggressively (rapid acceleration and braking)
Avoid excessive idling when you can.
Cold weather and frequent short trips can reduce fuel economy, since your engine doesn't operate as efficiently until it is warmed up.
Driving on hilly or mountainous terrain or on unpaved roads can reduce fuel economy. Avoid these if at all possible.