being ex-vauxhall and a big fan of the 1.7dti lump I think it would be possible, I love the way the estate version I had can out-eco a hybrid, produce sub 130g/km and all this from a salesmobiles with an engine thats been around since the very earlier eighties if not before( and is still going).
BUT that said I don't think it'll be a completely stock one. I think EXTENSIVE hypermiling techniques, trick tyres, long box, alternator slipper, different undertray (i know the Eco4's had a basic one over the Std cars) and maybe a trick ECU map matched with a shadow car providing a perfect draft...... but not carrying any any Opel decals/IDs
(guessing)
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good things come to those who wait, sh*t turns up pretty much instantly
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