In the very vast majority of countries in the world it is not meant to be allowed, but it is not prejudiceable (don't know if it's the right word... I'm no brit, damnit). Basically it's a very common way of avoiding licensing, you can either represent the name, the model, or the company that owns it, but not all of it at the same time, because in that case you make a "link" between the company and their property, therefore their image. You cannot be considere at fault by representing something that belongs to a company, even at a near-perfect copy, if you apply no other links to be made to that company. For car models, it's nearly comical : Porsche can't legally attack you for making a near-perfect 911, if it's nowhere said to be a Porsche. Lets say you call it a Mousche 822, with a proper own logo and badge : you got the model, but not the name nor the company. No link applicable. You didn't "specifically" looked to make a Porsche 911. It's a serious nightmare to judge on a legal point of view, so most of the time they let it go through (be aware of Ferrari tho, they went on court for less). On the other hand, you can spend how much time you want on a scratch-made car model, if it's clear as water that it IS a Porsche 911 with the Porsche badge, free or not, you're on a fragile soil. And if you ask money for it, you need a selling licence (depending on the country), a copyright licence (you probably don't have it considering the price), and a fair amount of paperwork (good news the digital world is still quite uncontroled, am I right?).
But yeah, the funny part is when a modder is defending himself because of the "SO MANY HOURS" he worked on his thing. I mean... Thanks and all, no doubt about that, but... Never forget your situation.
"Officer, I should have the right to sell my drugs, it took me so many hours to make it" - well, that doesn't change much of it, ya know. do you have a permit to sell it ? No ? YOU DON'T SAY