A sub-tank fuel system is an auxiliary fuel tank that increases a vehicle’s total fuel capacity. While rare in standard passenger cars, it’s more common in heavy‑duty SUVs, off‑road vehicles, and utility trucks designed for long‑distance or remote‑area travel.
How a Sub Tank System Works
- The main tank supplies fuel to the engine.
- The sub-tank stores additional fuel and can transfer it to the main tank via an electric pump or selector valve.
- The driver controls the transfer using a dashboard switch, and some vehicles have a separate gauge or indicator for the sub-tank.
Vehicles Commonly Equipped With a Sub-Tank
Toyota
- Land Cruiser 70 Series – Many variants in Australia, Africa, and the Middle East.
- Land Cruiser 80 Series – Certain non‑U.S. models.
- Land Cruiser 100/105 Series – Available in some diesel and utility configurations.
- Hilux (select models) – In certain markets for mining and remote work.
Nissan
- Nissan Patrol Y60/Y61 (GQ/GU) – Popular in Australia and the Middle East.
- Nissan Safari – Japanese market version of the Patrol.
Land Rover
- Land Rover Defender (older models) – Some expedition‑spec versions came with dual tanks.
Other Utility and Expedition Vehicles
- Toyota Troop Carrier – Common in Australian outback and African safari operations.
- Overland‑modified SUVs and trucks – Often fitted with aftermarket sub tanks for extended range.
Why Sub Tanks Are Used
- Extended Range – Necessary for travel in regions with few fuel stations.
- Safety – Backup fuel source in remote or extreme conditions.
- Convenience – Reduces the need for carrying external fuel containers.