My advice in your shoes would be to just keep your low mile still warranted car for as long as it suits your needs
Keep it serviced and those picantos run for yrs
See how things pan out over the next 18 months and if later on you find you need a WAV vehicle then you can take the mobility scooter/wheelchair along with you, the AP on WAVS are high but keeping the Picanto will help to offset this
Hope this helps