Had the Clio tuned the other week. Took it on a run from Walsall to Watford and in the 107 miles it returned 37.3mpg!
That's like the most I've ever seen it do.
Mind you I was driving like a sane human - stuck to 65-70mph with a couple of overtakes. It was also a nice cool evening and mostly downhill. But even so, I'm amazed.
Used slightly more on the way home this afternoon due to traffic and doing the same journey in about 3/4 of the time...