GoodCleanTech has a post on the SmartGauge in the 2011 Lincoln MKZ hybrid that add long term fuel efficiency monitoring to the real time MPG numbers.

2011 Lincoln MKZ Hybrid to Get Upgraded SmartGauge
Categories: Automotive
The upcoming 2011 Lincoln MKZ hybrid, which is based on the existing Ford Fusion hybrid, will feature an updated SmartGauge layout, AutoblogGreen reports.
The twin 4.3-inch LCDs will bracket a centrally mounted speedometer as before. But the gauges will feature a newer, green-gold design, plus long-term efficiency indicators in the form of apple blossoms.
You read that right: after the first 4-6 weeks, if you've been driving efficiently over time, the first flowers will begin to appear.
The flowers start out as little buds, and then grow into smaller and then finally larger flowers, the report said. According to Ford, earning all of the flowers on the display means you saved about $8,000 in fuel costs and 30 tons of CO2 emissions over the lifetime of the car; I imagine that last achievement will take a while.

In this instrument gauge to the right is the SmartGauge.

The idea is good, but a challenge to apply to data center efficiency monitoring in there isn't a simple metric like PUE that measure the overall efficiency of resource consumption and work done.

Lincoln did usability testing to figure out this gauge. There are ways to develop a gauge like this for data centers, but it requires integration of the work performed by the data center which requires a visibility to the SLAs for services run in the data center.