I am rather surprised you implied that the two state Bentley's will be retired in 2027. King Charles was using one of the Royal Cars that has been in service for 75 years having been ordered by the late Queen in 1947, from Rolls Royce. So, the Bentley's are only 20 years old. If you look at the previous Rolls Royce state cars, they are still in service. The Queen had new RR in about 1958 approx and then a new on in mid 1960's and one for her Silver Jubilee in 1975. Which are still in service in the royal muse. At the Sandringham the late Queen has cars that belonged to Her Mother and Father + Queen Mary. even one belonged to King Edward VII her Gt Gt Grandfather.