Speed Week: BMW M4 vs Porsche Cayman GTS

Which means the Cayman feels the happier of the two at Castellolí, but there's one massive niggle that I can't shake. The GTS hasn't moved the game on as much as we'd hoped it would - oddly, and perhaps perversely, the stock Cayman is almost too good. It's the default, sensible choice, but somehow no one gets out of the little Porsche with any burning passion for it. It's all thoughtful nods and slightly weary respectability. The BMW, on the other hand, is somewhat more flawed on track but eminently more intriguing. It requires more analysis. And while it's not as epic-feeling pounding a circuit, it feels like it might come into its own on the road. Which is handy, because the next part of TG's Speed Week happens to contain...

(Words: Piers Ward, Photos: Mark Fagelson)