I had an Opel Astra diesel in the driveway last weekend. The economy meter changed from mpg to gal/hr at idle. It was pretty cool. I believe its a 1.9 turbo.
.2 gal/hr
Photos
Also had a 07 BMW 320d with the 2.0L twin turbo diesel / 6-speed stick. That was unbelievably quick and fun to drive. Didn't get any pictures of it.