I'd also say that too Toplad.
My Z4 is slower on most roads than most cars without really trying to maximise it's performance.
That is the CORE point of a sports car imho, it takes time to master and it relies on your putting in the work to get the best from it. Personally, if the Z4 was 'easy fast' like a hot hatch, I'd hate it. I actually like the fact it is a challenge to go quickly, because my last hot hatch was ultimately too easy to go far too quickly without even trying... that made it completely flawed for an enjoyable drive out because you were through the speed limit within 7 seconds and doing it all without even starting to 'enjoy' the car or having to work it hard to do that.
My commute sends me down some fun back roads, my last car would push 90mph down the road if I wanted, and be quite planted and solid doing so, the Z4 on RFT's and I'd bottle it at 50mph, now maybe 70mph is plenty on the FK452's... it'd do 90mph, but with an iron will. THAT is a GOOD thing to me, it's slowing me down and making me enjoy the driving, and making me have to work hard to go quickly, and arrive at a destination reeling with the challenge, rather than getting out calm and collected with little thrill but having blown the speed limits away and ultimately just going fast because I could.
I'd put thrill of driving before ability to cover the ground any day in this kind of car. If point to point and just going quickly while likely having less fun than a low fun sports car is a core requirement in a car get an Evo IX and piss on anything else going on UK roads!
A standard 118bhp Elise is slow on the roads, but SO intoxicating to just drive for the sake of it. To compare it to a lardy, vague, bloated Astra VXR for point to point speed would be stupid, and much the same holds true for the Z4... it's just a totally different type of car, and I'm surprised the OP actually cares how fast their car is compared to a bland hot hatch! (if these kinds of concerns even entered my mind I'd have not bought a Z in the first place, an Evo would have been on my shopping list

)
Dave