Regardless of which end of the country you're buying in, there are sizeable differences between similar cars for sale in the same region.
We found that some dealers charged as much as 2000 more for a BMW 3 Series than a rival. Even car supermarket prices varied, with a difference of about 1700 on a Nissan X-Trail.
Optimistic private sellers were the worst of all sellers for over-valuing their vehicles, with some charging as much as 3000 more than a similar car elsewhere.
Best plug-in hybrid cars 2021
Plug-in hybrids can reduce fuel consumption to an absolute minimum, but which models are the best all-rounders and which should you avoid?
Audi E-tron Sportback long-term test review
Can you live with a fully electric car if you can't charge at home? We're finding out with the help of the Audi E-tron Sportback