With CarWow, when asking for quotes, you put in manufacturer and type, engine, trim and options (including colour). The quotes you then get back from dealers are against that specific spec. The examples (before you put full details in) are intentionally not specific, which is perhaps the stage you're at?
If you want clarification, you can then message individual dealers who have quoted. The ones I've messaged have all got back within a business few hours (some within minutes). Its useful once you've worked out what you want, as a start point for haggling.
With electric cars, to make CarWow sound better, the government grant is in the headline discount that CarWow has found (so that immediately means that "CarWow" can save everyone £3500 as that is the government grant...).
My point about the percentage, is some manufacturers add 7% to the factory price to get to a RRP (so a dealer would make 7% profit if they sold at the RRP). Others add different amounts. So for different cars, more dealer discount is available. Can be a bit of work to get that % number so to know how much to haggle
Some manufacturers (and probably specific chains) also have special "schemes" which can play with the price (scrappage schemes, finance schemes, etc) but CarWow wont go into that sort of detail. Hence why you may get additional discount by talking directly. In the end - its the amount of money you pay that matters - not what "scheme" you're on!
Of course, dealers have lots of ways of representing prices to suit themselves. I had one show me a printout (which of course I couldn't take with me) which said that they would make zero profit if they sold at a particular price (to convince me that the other dealership would be making a loss at the price quoted). I then had a third say that the same price (options, etc) would give them 1% profit, which to me seemed more honest (ok - oxymoron with car sales). The one that quoted "at a loss" then wouldn't honour price, take calls (etc) and "forgot" about agreed meetings, so the "at a loss" may have been true. Decided i didn't want to deal with someone like that anyway.
The advantage of CarWow is that its dealers from across the UK competing, which saves you a lot of initial phoning around. I ended up getting a dealer in Ayr who wasn't in CarWow to better a price that a dealer on South coast of England (so lower delivery costs) quoted at via CarWow. The Ayr dealeralso knew the systems well enough to reconfigure a car already in production rather than starting configuring a car from scratch, which brought the delivery date in by 2 months, compared to the 5 other dealers I spoke to.
2nd hand market is of course a different ball game entirely.