It's not weird, it's an anti-competitive practice. It's a bit like what France (I think it was France) did in the early days of the VCR industry: the French government required all imports of video players from the far east into France to come through one tiny customs post - high in the Alps if I recall.
There was no good reason for this - it was just a thinly disguised attempt to slow the speed of imports and thereby support the French electronics industry.
Differing rates of taxes and duties mean that the same car will be sold at wildly varying pre-tax prices around Europe. Manufacturers and national distributors do not want consumers to take advantage of those differences by shopping abroad. However, EU (and other domestic)competition law requires that they be allowed to, with stringent penalties for breaches of competition law (including criminal convictions). Eg, back in March 2004, Microsoft was ordered to pay 497 million euros for breaches. Which was a lot of money in 2004.
So instead manufacturers and suppliers will try weasle ways to put people off buying from abroad. Offering insanely long lead times is one way.
I would suggest that the OP does two things: first, speak to a dealer in Norway and find out when a car built to your spec could be delivered. Second, get a friend in the UK to do the same thing (but right hand drive).
If the two estimates are the usual 10-12 weeks, then you have very good prima facie evidence of anti-competitive practices. Whether you then decide to do anything about it (such as speaking to Fiat customer services and saying that if you don't get your car from a UK dealer within 12 weeks you will report them to the Competition Commission) is up to you.
PS It does not matter that you are in Norway which is outside the EU - if the practice is affecting competition in member states then the Competition Commission has jurisdiction to act. And Fiat is of course in the EU.
