The Prince of Wales has described the birth of the Duke and Duchess of Sussex’s daughter as “happy news” as he highlighted the importance of leaving a sustainable legacy for future generations.

Charles commented on becoming a grandfather for the fifth time following the birth of Lilibet “Lili” Diana Mountbatten-Windsor during a visit to a production plant for the Mini at Cowley near Oxford.

The heir to the throne also joked about the vehicle, paraphrasing the words of Sir Michael Caine’s character from the 1960s movie The Italian Job.

Charles, who drives an Aston Martin sports car converted to run on surplus wine, said at least he had not “blown the bloody doors off” an electric version of the Mini when he took if for a brief test drive.

During his visit to the plant Charles met staff on the production line as he marked 20 years of modern Mini production.

After he drove a new green-coloured electric Mini off the production line he gave a speech to assembled workers and apprentices.

The prince said: “The development of technology like electric vehicles, or green hydrogen for that matter for heavy transport, is vital for maintaining the health of our world for future generations, something I’m only too aware of today having recently become a grandfather for the fifth time.

“And such happy news really does remind one of the necessity of continued innovation in this area, especially around sustainable battery technology, in view of the legacy we bequeath to our grandchildren.”

Charles had driven the Mini slowly off the production at just a few miles an hour and turned left after about 20 metres before stopping.

He added: “If I may say so at least my test drive a moment ago was on the whole without incident and only went to prove that the new Mini is silent but deadly and also a very good colour indeed.

“And to paraphrase the immortal words of Sir Michael Caine ‘at least I didn’t blow the bloody doors off’.”

Lili, a younger sister for the Sussexes’ two-year-old son Archie, was born at 11.40am on Friday at Santa Barbara Cottage Hospital in California, weighing 7lb 11oz.

She is the most senior royal in the line of succession to be born overseas and would be eligible to become president of the United States.

In his speech, Charles highlighted how the Duke of Edinburgh was a pioneer in the use of sustainable vehicles: “Twenty years ago, an electric Mini would have seemed impossible, and yet I understand that, by 2030, Mini will be the first BMW Group brand to go fully electric.

“Incidentally, my late father, the Duke of Edinburgh, used an electric vehicle based on the Bedford Lucas CV as early as 1981, and of course famously drove his eco-friendly liquid petroleum gas-powered Metrocab all over London – it is now on display in the museum at Sandringham in Norfolk.

“And for all its worth I have been running my 51-year-old Aston Martin on surplus English white wine, and whey from the dairy industry, for quite some time – which has meant that the Aston Martin engineers have had to admit that, much to their surprise, it runs better on that fuel than it did on petrol!”

The prince spent the day in Oxford and earlier celebrated the contribution of female students to life at Oxford University with a visit to Somerville College, established 140 years ago as a place for women to study.

He also toured Oxford Botanic Garden, in his role as the attraction’s patron, a visit that marked the garden’s 400th anniversary.