What does the DISP button do in a car?

The DISP button on a car's dashboard or steering wheel controls the information displayed on the vehicle's trip computer. In UK models like the BMW 3 Series or Nissan Qashqai, pressing DISP cycles through displays showing mileage, fuel economy, remaining range, and other driving data. Most modern vehicles display key information like: 1) Current and average MPG (miles per gallon) 2) Remaining fuel range in miles 3) Trip distance and duration 4) Outside temperature. The warning light you mentioned is actually the power steering warning - it should turn off after engine start. If it remains illuminated in vehicles like Vauxhall Corsa or Ford Focus, it indicates a potential power steering fault that needs diagnostic checking.