So... if they didn't have the Motability lease car... they'd still get the exact same money as part of their PIP claim, saving you, the taxpayer (one assumes) nothing.
Which means what you're mad at, is that there is a scheme whereby disabled people have access to affordable vehicles.
They are new vehicles because supplying second hand vehicles would cost more in maintenance than it is worth, and would be a royal pain in the arse, and new vehicles handed back, are then sold on, the funds then going back into the Motability charity, and the second hand vehicles benefiting the general economy and the second hand car buyers.
This is important because disabled people generally have fewer transport options, can't access public transport reliably, may well need to visit hospitals more often and so really need a reliable vehicle.
Should it be means tested? No, because those who really do earn so much that the PIP payment or childs DLA payment makes no odds, will be paying back far far more in tax than they're costing.
For everyone else, they need it, being disabled is expensive and means testing would cost significantly more than it would ever save.
Bottom line, you are jealous of disabled people. Sit with that. You're jealous, why are you jealous? Do you think disabled people don't deserve help? Do you think they're getting a better deal than you? Do you think you, a fit healthy person should, by rights be doing better than a poor sad broken disabled person who is of no real benefit to society... perhaps?
1 - Motability do not GIVE people cars, they lease them, you pay a lot for them in advanced fees and monthly lease fees, you give it back after 3 to 5 years or 5 to 7 years for WAVS, and you start over, finding another advanced fee (if you don't qualify for a grant, and few do).
2 - Grand reveals, never heard of that happening unless you mean a car salesperson chuffed at making a sale hands you the keys and goes 'ta daaaaa' and does jazz hands (none ever have but I guess they could).
3 - A big charity in the UK buying cars, maintaining them and selling them on to the public is a really fucking good thing for the economy and second hand car buyers. What do you think losing 1/5th to 1/7th of car sales, new or second hand, will do, how will that benefit anything?
4 - No one is GIVEN a house by the local authority - they are given tenancies for which they pay rent. Where that rent comes from varies, but if they stop paying it they will lose their tenancy, same as anyone else.