The Duke of Cambridge came face-to-face with one of Prince George's dream projects on Tuesday - a life-size Lego model of a new McLaren's supercar.
The Prince took a break from parental duties with a tour round the automotive company's high-tech design and production centres in Woking, Surrey, where chief executive Mike Flewitt introduced him to their newest road vehicles.
William was clearly awed by the 280,000-Lego-brick version of McLaren's new 720s road car, and said: "Wow! My son would love this!"
He added: "My son's very into Lego and he'd love this: it's incredible!"
But the Duke was also treated to a grown-up view of the real version of the car, and took a seat behind the steering wheel to test out its interior controls.
"I am a car enthusiast," he said.
"I don't know very much about cars, but I like speed."
But when it came to finding out about the gadget-filled dashboard William made it clear what his customer priorities would be.
He asked: "The key question is: does it have a coffee cup holder?
"It's a fast car," he joked, "but does it have a coffee cup holder?"
In a comprehensive tour of the the site's innovative design area and production floor, the Duke was also given the opportunity to put the finishing touches on another model of the £210,000 720s, fitting its iconic badge to the front bonnet.
However, he admitted he was not quite sure of his sticking abilities.
He said: "Someone's going to be driving along and it's going to come flying off!"
William, who left his role as an East Anglia Air Ambulance pilot this summer, took a keen interest in the car's aerodynamic design and asked about the company's priorities when it created new vehicles.
Mr Flewitt said: "A lot of his knowledge is actually from aircraft and he was drawing parallels with what he knows from helicopters, aeroplanes and that side of the world."
But when the Prince was shown McLaren's brand new 570s Spider supercar, he quipped that its ability to reach top speeds of 200mph might just be hampered by one important detail - the law.
"Of course, there's a 70mph speed limit with that," he said.
In addition to seeing famous models of McLaren's racing cars through the years, including Lewis Hamilton's world-championship winning MP423, the second-in-line-to-the-throne also met with star apprentice Alex Machin and other assembly staff, who fit each component by hand.
Machin, 17, is the Manufacturing Magazine Awards apprentice of the year, and told William about his training on the production line.
Mr Flewitt said the Prince seemed to have most enjoyed meeting some of the company's 2,100-strong workforce.
He said: "My impression is he really enjoyed that.
"He's such a naturally engaging guy. You can imagine at 17 years of age it's probably a little daunting.
"And they didn't find him daunting, so they'll probably be glowing today."