Negotiating a price on a used car with an independent dealer

[p_k_n]

Currently looking for a vehicle to replace my wife's 2015 Volkswagen Tiguan. A small but well regarded local independent dealer has a nice 2016 Cayenne with 67,000 miles for £26k. It's in great condition, excellent spec and FSH however they don't want the Tiguan in part exchange. I can always sell it privately but would prefer to part exchange for convenience.

I've also been on a few Porsche forums and feedback is that I should be negotiating at least 1 - 2k off the price, as the consensus seems to be that it's overvalued. With this in mind I've come here for some "independent" advice on negotiating a price with the dealer. I've ran WBAC and Motorway quotes on the Cayenne and they are offering 19.5k and 20.7k respectively. I think they base their offers on recent auction and CAP results? Is it bad form to use these prices to negotiate a deal?

I don't want to low ball the dealer but the spread seems quite significant and with the additional hassle of not getting to part exchange the existing vehicle as part of the sale, I'd prefer a better straight sale cash price.

[Nickp82]

If you want to be taken seriously, do not mention the WBAC values to the dealer.
The relevant comparison is what other cars of similar spec/mileage are priced at by similar dealers.

[DeuceDeuce]

I’d be looking for a private sale with Porsche warranty if getting the best deal is important.

[sherman]

Whats the WBAC price of the Tiguan?

Sell the Tiguan and turn back up at the dealership with £25k cash ready to go. Offer £22k as a starting point.
WBAC/Motorway price is the trade price.

[soxboy]

How does it compare to other identical models in the classifieds?

If you can show that you’ve done your homework and that there are others nearby that are a bit less then you may stand a chance.

There is no god-given right for a discount despite want some may say. You will get told to go forth if you mention WBAC prices.