@OmSigDAVID,
One other thing I hear from a friend who buys and sells cars for a living is that the EPA mileage estimates for the VWs they do sell in the US are way off (low), and that owners he asks about mileage on the turbo diesels claim they're getting just over 50 but that it doesn't matter where or what kind of driving, city and highway mileage are nearly the same.
Another thing anybody who's lived long enough notices is that the small cars of today are much heavier than the small cars of 1950 - 1970; "weight" is a word you never read or hear any more in auto ads. Build a small car with modern materials instead of steel everywhere, and you'd most likely get weight back down to beetle-bug and Hillman/Singer levels even if you kept the airbags and ABS. At that point, a 1.6L engine such as the UK VW ad describes SHOULD get most of 100 mpg, if it didn't, something would be wrong.