Good: great looking, classy interior, decent chassis

Not so good: engine not powerful enough, faces stiff competition

When we drove the refreshed BMW Z4 (with its blink-and-you-miss-it facelift) earlier this year we came away a little underwhelmed. Not with the car itself but more so with the model that was laid on for us to test. In its wisdom BMW had chosen the sDrive35is Z4 as the launch car and with a price tag north of €80,000 we immediately likened it to the Porsche Boxster, a car it cannot hold a candle to in either posing or dynamic terms. We did reason though that the entry level sDrive18i, introduced as part of the refresh, may well be the pick of the bunch.

Having spent a week driving it in Ireland do we still think it is? Well yes and no.

First the good news: you sit low in the Z4 - really low. So low in fact that you have to use the side sill to get out. You also sit quite far back, behind the long bonnet and with your posterior almost slung over the rear axle. This is proper, old-school roaster design at its best. The seating position means you are in tune with the car, fed more details about what exactly the tyres are experiencing at ground level. This feeling is no doubt boosted by the fact that our test car was an M Sport model with fettled suspension and 18-inch alloy wheels that are shod in rubber band style tyres. The ride therefore can be jarring over broken roads, but the level of feedback that the combo provides - both through the wheel and your backside - is appreciated. With a near perfect 50/50 weight distribution, this is a real driver's car.

Or at least it would be were it not for the engine. The turbocharged 2.0-litre petrol engine under the bonnet offers up peak power of 156hp and 240Nm of torque, which is positively anaemic when it comes to performance, but this can be forgiven if the engine sounds good. Unfortunately it does not. There is a gentle hum from the exhaust pipes on start-up but this disappears the moment you touch the throttle; even with the folding hardtop retracted and your head exposed to the elements there is little offered aurally that would encourage you to stretch the engine and head towards the 7,000rpm redline. When you do venture towards it the engine sounds strained, as if it does not appreciate the attention your right foot is giving it. For a car that looks so much like a sports car this is a disappointment and means that in sDrive18i form the Z4 is not a car for driving just for the sake of it; it is one for looking good in.

And wow does it look good. Our test car was helped by being painted in bright Valencia Orange and sporting an extended Alcantara/leather combo inside that brings even more orange to the proceedings, but even in more demure combinations the Z4 still looks good. Even better with the roof down, which is a job of just 18 or so seconds and can be completed on the move - assuming you are driving at less than 40km/h that is. The cabin is spacious (for a two-seat roadster) and the seats are supportive and positioned just right. There is a slight ergonomic problem with the placement of the key holder and a tendency to catch the key fob with your left leg while pressing the clutch, but that is only a minor hindrance. There is a much bigger problem for the entry-level Z4.

While the big hitting sDrive35is counts the Porsche Boxster as its rival the 18i variant comes up against other models that are as equally good at looking well. The Audi TT Roadster for example. While it may not come with a fancy tri-folding metal roof it can be ordered with a diesel engine so that fuel economy and looking good are not mutually exclusive. Externally it may not look as aggressive as the BM but the interior is on par at worst. Then you have the Mercedes-Benz SLK 200, a car that subscribes to the same long bonnet, slung over the rear cabin design as the Z4, yet offers 184hp from its entry-level offering.

Then there is the elephant in the room: the Mazda MX-5. It cannot hold a candle to the three German cars when it comes to prestige, looks or fit and finish, but the class would not exist without it and when it comes to open top motoring it is still the benchmark for many. What it misses out in terms of a classy cabin it makes up for in smiles per miles. It's the one I'd put my money on.