What mechanical feature did early Beetles use instead of a fuel gauge to warn of low fuel?

Early Beetles used a reserve fuel tap instead of a fuel gauge to warn drivers that the main fuel supply was running low.

The tap drew fuel through two different pickup levels in the tank. In its normal position, fuel came from the higher outlet. When the tank level dropped below that pickup, the engine began to sputter; the driver could turn the tap to the reserve position and access fuel from a lower outlet.

This system gave the driver a practical warning without an electrical gauge. It also provided a small emergency supply, typically enough to reach a filling station, but it was not extra fuel stored in a separate tank. The reserve was simply the portion below the normal pickup point.

The arrangement required drivers to remember to return the tap to its normal setting after refueling. Later Beetles adopted dashboard fuel gauges, making the manual reserve procedure unnecessary. A reserve tap is therefore associated mainly with earlier cars, not every Beetle made during the model’s 1938–2003 run.