Amy's Passat has a great trip computer that provides a lot of information like fuel consumption (average and current), average speed, driving time, driving distance and distance left with current fuel amount. One thing I learned recently is that most cars made since 1996 provide all of this information (and more) to a port located within a few inches of the steering column. To access it, all you need is something like the ScanGaugeII - Scan Tool + Digital Gauges + Trip Computers which sells for $169
"The ScanGaugeII is an extremely compact automotive computer designed to read and display information about your vehicle in real time.
Simply connect the ScanGaugeII to your vehicle through it's OBDII port using the included cable, turn the ignition key and the ScanGaugeII automatically connects to your cars internal computer - it's that simple."