What is the gearing in the V50 1.6 Diesel, is it quite long - 6 speed or 5 ?
Although the weight loss is quite intense the V50 is pretty heavy as standad so the overall gain probably isn't all that much. I've left all that stuff in my Fabia. You could think about taking out the reat seats if you are serious about less weight.
Keep an eye on the DPF with short shifting, I have read it can clog up. An occasional 'full beans' blow to clear it out may be worthwhile.
Good luck though, 50 MPG (US) should be within easy reach with that 1.6D engine and some coasting. I can get the average MPG on Mrs A's Octavia estate (2.0 litre) to read 60+ (UK) around town, I'm sure I could get it more on a run but I'm not allowed to drive it that far...
