Firstly, a vehicles may be considered abandoned if it is:
- Untaxed
- Has no valid MOT
- Has been stationary for a long time
- Is significantly damaged, run down, or un-roadworthy
- Burnt out
- Has flat tires
- Has mould on the inside or outside
- Contains waste
Secondly, the vehicle may have been used in a crime. You should not enter or touch an abandoned vehicle. Ideally you should inform the police so that they can do follow up enquiries maybe with the registered keeper.
You can then ask the Police, DVLA or local authority if they can track down the owner of the car so you can enquire about taking ownership of it.
Keep tabs on the car, if the DVLA can't track down the owner then the chances are, the car will be towed by an approved recovery agency and the towing company will auction it off to the highest bidder or put it through an auction.
In my experience of dealing with abandoned vehicles the process can take weeks, sometimes months and the costs of the recovery and storage, getting it back on the road, making it roadworthy, insured, taxed and a set of keys for the vehicle are more considerably more than the value of the vehicle and a lot more hassle than buying an honest vehicle through a dealer or private seller with all the paperwork and keys available from the off.