If looking to purchase a relatively recent car at auction it's worth taking in mind these tips:
1. Auctions have a peak time of day. For example WBAC is owned by BCA and their auctions are always held at the best time of day to achieve the most money for the cars - therefore these are usually the most expensive auctions. Big groups like Inchcape, Pendragon, Lookers etc will have their own auctions, usually with their own pecking order of their buying/p/x ability and the deal they've managed to work - the cost of the cars will be proportionate.
2. Disposals from franchised dealers/WBAC types/finance companies are normally going to be the best chance of a problem free car - in fact most include an AA health check before the auction for you to view for transparency. The further you go outside of these auctions the more likely you are to find problem cars being traded.
3. If buying from a branded auction and presented with a vehicle that the company has the brand of in group - ask yourself why. Remember the AA check only really picks up obvious mechanical damage, its entirely possible the car has been rejected from the franchises dealer on quality grounds for something that the AA check won't find.
4. The mileage and age of the car makes a big difference to its relative value at auction for a private punter. Most approved used car programs get expensive for vehicles that are over 60k or 5 yrs that means this kind of stock can be good value at the auction. Most dealers shy away from selling non approved same brand vehicles so 60-80k mile cars and low mileage cars over 5 yrs old can be good buys.
5. Research the auction list and ideally view the cars before entering the ring. Its a really fast pace so you need to set your price in your head before you enter, each auction is usually over in minutes. Do not wed yourself to one car, most people in the room are traders buying stock and it is not an emotional experience for them.
6. Remember auction charges are very high and most the regular buyers in the room are getting a discount on them so you are still paying a premium price for this car. Don't think that just because you've bought a car at auction it's automatically below the market value or even the forecourt value BCA and the like are very good at marketing their talents, often I've seen cars go for more at auction than I have exactly the same stock sitting on my forecourt for, and that's before charges - usually WBAC auctions.
7. Auctions are very seasonal, ideally go when nobody is interested - school holidays, week before a plate change, convertibles in winter, 4x4 in summer all ideal times for getting a real bargain. Combine to achieve the best results.