3 months is pretty standard. Very few manufacturers keep tons of speculative stock these days and if you want optional extras then they are almost always factory orders. Dealers can pull in cars from other dealerships, but will probably be less willing to do that for a Motability customer than a private customer, but worth asking. You do not have to have the car serviced at the supplying dealer and you return the car to the dealer that you get your next car from, even if it’s a different brand, so well worth travelling for a discount (we got our car from 70 miles away but saved £500 by doing so). We are 20 miles from a main dealer, but they collect and return the car from/to our house (almost all do), so distance from dealership shouldn’t be an issue either.