I would not worry to much about short journeys and DPF as during the Winter I do many days of not more than 5 miles if that and never had any problems in my Seat Leon with 1.6 Tdi engine though I suppose its something that niggles in the back of our minds. My previous car to the current one was petrol but only switched to that because the council want to ban diesels in town but I’ve switched back to diesel on my current car simply because nothing else was suitable for what I need.
With your grant for a scooter I wonder if you were turned down because the government in all there wisdom does not recognise mobility scooters as a disability aid like they do with wheelchairs. It’s one of those discriminating things where they see no problem discriminating against we scooter users (I assume because a lot of bone idol non disabled folk use them too) but not having the use of my left arm/hand/fingers I can’t use a wheelchair with one hand but I can push and pull the speed controller on my scooter.
I’m thinking of going the grant way myself next year because of the lack of suitable cars but as long as the VW Touran holds it’s AP price I might just about manage its AP along with the adaption I have to have that Motability are proud to say “are free” when in reality they maybe subsidised but there nowhere near being free.