I bought my MX-5 through them 3 years ago. The only contact you have with them is to confirm the order details and discuss available colours- I couldn't have my first choice and ended up choosing a different colour. Once this was decided, I was told that the Mazda dealer would contact me within 2 days.
The dealer did ring to introduce himself and told me that he was in Carlisle (I live in Lincolnshire!). I paid my deposit (it was more than the £500 quoted but I did have added options on the car). From that point on, you only deal directly with the dealer, although it is frustrating only having the option of telephone contact due to the distance involved. I ended up driving up to Carlisle with my husband to collect the car, as I did not fancy some numpty driving my brand new MX5 to me. The delivery included is driver delivery. The dealer would not budge on offering free trailer delivery. I found that the dealer would not budge on anything as the car is being offered so much cheaper that their profits have been cut to the max and therefore they have no more room to negotiate. Having said that, I got a car with extras that cost me less than the basic RRP. I think I paid a couple of thousand less- definitely worth doing.
At the end of the day, you are equally as likely to have good service and experience as a bad one as you are still dealing with the franchised dealer- just not a local one. It all comes down to the luck of the draw. You have to decide whether you want to save a couple of grand and risk hassle or go local and pay more. There are no risks- you pay the dealer not the internet company- he gets the commission direct from the dealer. Happy hunting. Hope this helped.
By the way, Patch007 is on another thread for uncardiscount, recommending other internet companies, including drivethedeal, so I agree, he is definitely connected to them and should be ashamed and removed. This is supposed to be honest advice between consumers, not dealers plugging their own companies with false testimonies!!!