BMW Z4 18i

These latest revisions have breathed new life into the Z4. It’s not enough to beat the Audi TT but in 18i and 20i guise, the BMW is both desirable and engaging, and won’t cost the earth to run. However, range-topping versions can’t hold a candle to a Porsche Boxster.

If you want classic summer driving thrills, then a road-hugging roadster ought to be ideal. And with its traditional two-seater layout, simple rear-wheel-drive handling and versatile folding hard-top, the recently revised BMW Z4 fits the bill perfectly.

However, even eagle-eyed fans will struggle to spot the tweaks to the exterior. In fact, apart from the revised xenon headlamps and grille, the BMW’s looks are virtually unchanged. That means you get the same long nose, low-slung stance and eye-catching combination of creases and curves.

Like its Mercedes SLK arch-rival, the Z4 has a folding metal roof, which promises to blend open-air thrills with coupe comfort and security. It’s easy to make the most of any sudden sunshine, too, as the top can be raised and lowered on the move. Unfortunately, due to the two-piece roof’s complexity, it takes a leisurely 26.4 seconds to stow the hood.

Peer inside the BMW and you’ll find it’s been left largely unchanged. That’s no bad thing, though, as the dashboard is attractive and quality is top notch. Only the slightly dated buttons and stereo display betray the car’s advancing years. Bluetooth and air-con are included, but you’ll pay extra for kit like the wind deflector (£215) and heated seats (£295) – both key in a convertible.

The combination of a low seating position and high transmission tunnel gives the interior a snug feel, but there’s actually plenty of room. There’s a decent amount of storage, too, including a long shelf behind the rear seats and a large, lockable cubby. Better still, with the roof raised, the Z4’s boot will swallow 310 litres of luggage – although this shrinks to a cramped 180 litres when the roof is lowered.

Still, most roadster buyers are more concerned with back-road thrills than boot space – and the BMW doesn’t disappoint. The new entry-level 154bhp turbocharged 2.0-litre engine feels sluggish at low revs, but selecting Sport or Sport+ modes sharpens the throttle response and adds weight to the steering.

At the track, our entry-level 18i model completed the 0-60mph sprint in a brisk 7.9 seconds, but buyers wanting more performance can choose from the 181bhp 20i or 242bhp 28i. Plus, there are the six-cylinder 302bhp 35i and 335bhp 35is models.

Yet whatever version you choose, you’ll get the same balanced rear-wheel-drive handling, plus steering that’s direct and delivers decent feedback. A snappy gearshift and surprisingly sporty exhaust note add to the fun.

The Z4 delivers decent refinement, too. There’s little wind buffeting with the optional deflector in place, and raising the roof brings more calm. It’s not coupe-quiet, though, and the ride is a little firm, while the restricted suspension travel can cause hops and skips over mid-corner bumps. It’s expensive, too, with prices from £27,610 – over £1,000 more than for an Audi TT Roadster.