I agree with what @Jojoe has said, in that the 15,000 mile rule has aways been a very relaxed!
Even today if you you are coming to the end of a 3yr lease and on target to hit 60,000 miles, Motability isn’t going to kick you off the scheme whils’t you wait upto 18 months for your new vehicle arrive and tell you to come back when it arrives or kick you off the scheme just because you haven’t chosen a new vehicle yet!
Should you choose to extend your vehicle to 5yrs there is no reducton in yur sacrified benifit payment, meaning you pay an extra £7,384 of sacrified benifits based on 2023/24 rate. This will go to maintaing your car and have an allowance within it for additional depreciation over the extented lease.
You haven’t said how many miles you are likely to do per year however, if you still have any uncertainty contact Motabilty via email or social media for an answer 🙂