I did the Taranaki ride this year. It was FABULOUS. It also happened to be the hottest part of the entire country that day! We did it in 5 hours 17 minutes at 33 degrees and drank around 5 litres of sports drink! I swear it took me a few more litres after the finish before I needed to pee! Complete contrast to the Taupo Challenge which was freezing (and took me 6 hours!)

About 3000 people took part and it was a great ride, well organised with enough groups at different speeds that you could latch onto. It was gently undulating at the start for about the first 50km or so, then it really did level off with long gentle inclines. These made you feel like you were cycling into a headwind or in treacle as you just couldn't get your speed up, but it wasn't really a slog and you didn't realise you were going uphill. It was only when you started flying down the long descents to the finish that you realised you had been climbing for ages! The finish is great fun.

I do recommend it.
You can park in the side roads around the racetrack and avoid the main park area if you want.