When we set out to document the most extravagant options that you can choose for your new car, we expected it to be a straightforward exercise.
We would get price lists for the various luxury and high-performance cars and trawl through them. Reckoning on much of this information being available through online configurators, we could fill in the gaps by contacting press offices.
Little did we know that in most cases, pinning down what you'll pay for extras on your Bugatti or Rolls-Royce would be pretty much impossible, with such information a closely guarded secret. Even the press kits for our test cars often omit this information. But undeterred we pressed on to find out what we could, even though some marques that should be here are absent.
However, we have managed to find plenty of eye-wateringly costly options including paint jobs, brake kits, carbon fibre body kits and much more. So if you want to know who charges £7500 for a yellow paint job or nearly £9000 for a sports exhaust, read on:
Ferrari: Historical colours
Over the years Ferraris have been painted in an array of liveries that have become iconic, and you can now specify them on your new Prancing Horse. So if you want bright metallic green, blue with a white stripe or even brown you can pay a hefty £7104 on your Portofino, 488 GTB or 812 Superfast for the privilege.
Ferrari: parking cameras
If you're buying a Ferrari Portofino, 488 GTB or 812 Superfast you'll want to look after its bodywork and what better way to do it than by investing in parking cameras front and rear? But to do so you'll have to pay £3456.
Bugatti Chiron Sky View
When Bugatti revealed that Chiron buyers could specify a pair of glass roof panels for their £2.5 million hypercar, it didn't disclose the asking price. We still don't know, but we're pretty sure it's well into five figures.
McLaren 720S: carbon fibre
Shaving a few grammes off the kerb weight of a McLaren 720S might seem rather pointless, but if you've got a spare £58,900 to spend on carbon fibre why not go for it? Included in that cost are lighter door mirrors (£2220) and rear bumper (£4480), while a diffuser and front splitter are £5990 apiece.
Ferrari: panoramic roof
A lot of top-spec mainstream family cars now come with a glass roof as standard, but if you want one on your Ferrari GTC4 Lusso you'll have to pay £11,520 for it.
Mercedes-AMG ceramic brakes
The Mercedes-AMG GT 63 4Matic four-door has a pretty awesome set of brakes, as you'd expect of a 639bhp slingshot. But the £140,000 super-saloon is available with a set of ceramic brakes for £7000 which admittedly is only 5% of the cost of the car – but it's also most of the cost of an entire Suzuki Celerio.
Audi RS6 ceramic brakes
Again, the Audi RS6 has some pretty impressive stoppers, but if you want to absolutely cane your fast estate every time you take it out you'll probably want to upgrade to ceramic brakes. At £9375 the cost of this extra equates to a hefty 11.5% of the list price of a standard RS6.
Ferrari: golf bag
If you need a golf bag you could nip round to Sports Direct and snap one up for a tenner. But if you want an official Ferrari one to go with your 812 Superfast you need to prepare yourself for a £6240 bill. Although to be fair, the Ferrari bag is rather more a work of art than the Sports Direct alternative.
Bentley Bentayga entertainment
For most of us, rear-seat entertainment means a £50 screen stuck to the back of the front seat, but not in the Bentayga SUV where it's all beautifully integrated (naturally). And for this you'll be relieved of £5635 at purchase time.
Mercedes-AMG GT paint
Buy a Mercedes-AMG GT coupé or roadster and you can have black or red paint as part of the deal. Various metallic finishes are available for an extra £945-£2145, but for some reason if you want metallic yellow you'll have to pay a whopping £7500 for it.
Ferrari: Apple CarPlay
A lot of mainstream cars now come with Apple CarPlay and you don't have to spend a fortune to secure something with it. Ferrari was the first car maker to offer such tech, on its FF in 2014 (pictured here); if you want it on your 488 GTB you'll have to pay £2400 for it.
McLaren 720S: Various
You'd think that paying more than £200k would net you electrically adjustable seats as standard but no: they're a £2730 option. An around-view camera system is £2480 while one of the most popular extras is a £2070 lift system to protect the front splitter on uneven ground and steep multi-storey car parks.
Ferrari: fire extinguisher
Shop online and it's not hard to find a decent fire extinguisher for £20-£25. But Ferrari charges £624 for an official extinguisher for its 488 GTB; that compares with £150 for a McLaren extinguisher.
Lamborghini Huracan body kit
You might think that the Lamborghini Huracan is aerodynamic enough, but for £20,396 you can buy a body kit which will apparently "Generate immense downforce at high speeds and head-swivelling attention at any speed". The kit includes aggressive front splitter, side skirts, rear diffuser and rear wing in a strong, lightweight black composite.
Of course there are plenty of exclusive luggage brands that charge thousands for bags and cases, but the idea of spending £4123 on a Mercedes-Maybach-branded calf-skin bag still grates. Still, it's a lot cheaper than that Ferrari golf bag.
BMW 7 Series rear seats
The rear of a BMW 7 Series isn't a bad place to spend time, but if you want the full luxury experience you'll want to swap the bench seat for two individual chairs separated by a centre console. BMW will also bung in heated, ventilated and massaging seats plus a bit of entertainment – as long as you're happy to pay £8425 for the privilege.
Lamborghini Huracan wheels
For that authentic racing look you can fit a set of 20-inch centre-lock alloy wheels to your Lambo. You'll have to pay a £7693 premium over the standard wheels – and for them to fit you'll also have to pay another £4103 for a centre-lock conversion.
Mercedes-AMG GT carbon fibre
Any high-performance car worth its salt now has to come with lashings of bare carbon fibre (CF) exterior panels. Buy a Mercedes-AMG GT four-door and you can pay £3895 for a CF front splitter, rear diffuser plus CF inserts in the side skirts and front wings. Then, once you've done that you're eligible to fork out a further £3265 on carbon fibre door mirror housings and a fixed rear spoiler.
Lamborghini Huracan exhaust
With its 602bhp V10 the Huracan isn't lacking in power, but for £8889 you can have an official sports exhaust that's claimed to be 10% lighter than the standard set of pipes and capable of boosting peak power by 5%.
Want to make your £175,000 Mercedes-Maybach S-Class look like a 1957 MG Magnette? Then you're in luck, because for a trifling £12,800 you can invest in a two-tone paint finish with a choice of nine different colour schemes.