Fabs, back when Motability didn't dispose of their own cars, but just dumped them back on their dealerships, they wouldn't pay extra for metallic paint. Funnily enough, as soon as they chose to remarket their own stock, they changed the policy!
However, back in the day, non-metallic dark blue was frequently known in the trade as "Motabilty blue", as well as "Doom blue' and "90-day blue" ... because that's how long the big dealer groups traditionally held their used cars before they traded out the stuff they couldn't sell!
As for haggling, it's dead easy. Do it with a smile, respect the other side, and take a bit of time and you'll probably end up with a good enough deal from everybody's point of view.
I've just seen Sammy's post that he's not prepared to waste any time visiting dealerships when he's spending tens of thousands of his own pounds. If my time were that valuable, I'd happily employ a personal shopper or pay a bit over the odds!
Instead, I was quite pleased when haggling for carpets and kelims in Morocco this year, that someone hissed at Yv "Your husband bargains like a Berber!"
I don't doubt I paid more than I absolutely had to, but I think I paid rather less than most other tourists. Equally I don't doubt the vendors had some profit out of me, but that's what they use to buy their food and clothe their children!