Senior executives at BMW will privately admit that the underpowered Z3 fell short of the company’s boast of producing the “ultimate driving machine”. With the introduction of its replacement, the Z4, in the spring of 2003 the German car maker returned to form.

The Z4 was bigger, better built and quicker than its predecessor, and despite its long nose and stubby rump boasted “perfect” 50/50 weight distribution. Under the bonnet BMW went more upmarket, dropping the option of four-cylinder engines in favour of a selection of smooth six-cylinders.

From launch a 2.5 litre 192bhp and 3 litre 231bhp unit were available, soon joined by a 170bhp 2.2 litre.

While none of these models could be described as sluggish it’s the 3 litre that puts the biggest grin on your face and gives the BMW Z4 the performance — 0-62mph takes 5.9sec — to tempt owners away from a Porsche Boxster. In terms of fuel economy the 3 litre is virtually identical to the 2.5 litre (30mpg compared with 31.7mpg) and only a fraction behind the 2.2 litre, but the best news is that despite a hefty £4,000 premium when new, a 2003 53-plate 3 litre will today set you back only about £1,200 more than an equivalent 2.5 litre.

Unlike the Z3 the Z4 is great to drive and BMW included two electronic systems for enthusiastic drivers. First a Sport button that activates Dynamic Drive Control, a system that sharpens the throttle response and firms up the steering, and second Dynamic Traction Control, which can be adjusted to allow drivers to experience a little power-induced oversteer without getting into trouble. The only downside to the ride is the electric power steering, which can feel a little off the pace and slow to react, while the seats could have done with more lateral support.

With the Z4 approaching its third birthday in the UK the initial rush to buy has subsided and used examples are becoming more plentiful. As a consequence prices have started to look more reasonable, with high-mileage 2.2 litre versions dipping below the £15,000 mark for the first time.

It’s important to buy the right used car if you want an easy job selling it later. Service history is crucial; variable service intervals mean that the books should be checked carefully — speak to the servicing dealer if possible to confirm the authenticity of the stamps.

Colours and specification are also crucial in the second-hand convertible market; leather interior is essential and the car sits better on the optional 17in rims than the slightly weedy 16in. Non-metallic paint finishes are much less desirable, as is yellow; traditional blues and silver tend to fare best.

While standard cars were pretty well equipped some owners were tempted to tick the option boxes. Few add much value to the car. Upgraded stereos are nice, but don’t pay too much for them. The Bluetooth system is of little consequence either way and should not command a price premium, and satellite navigation should add no more than £500 to a car’s asking price.

The BMW Z4 represents a huge step forward compared with the Z3, and as the new version of the Z4 coupé is readied for launch in July (the roadster is already on sale) second-hand prices of this first-generation model are set to become even more attractive.

Run-flat tyres Standard on all models so no spare wheel to check

Seats Comfortable but lack lateral support

Boot space The 240-litre boot isn’t huge but can carry two sets of golf clubs

Roof Electric folding roof is beautifully made and quick to operate. Excellent fit and tight seals also make it a car that can be parked outside all year round without fear of water leaks

Sport suspension Standard on 3 litre models and an option on other derivatives. Strikes a good balance between comfortable ride and improved handling

Upholstery Leather essential

Rear tyres The 3 litre models are heavy on rear tyres. Expect 12,000-15,000 miles from a set

Oil consumption Keep an eye on the level and don’t rely on the dashboard indicator

Storage Cabin has plenty of space for occupants but is sadly lacking on useful storage space

Gearbox Manual as standard but auto box works well for extra £1,000 used

VITAL STATISTICS

Model BMW Z4 3.0i SE
Engine 2979cc, six cylinders
Power 231bhp
Transmission Six-speed manual
Fuel 31mpg (combined)
Acceleration 0-62mph: 5.9sec
Top speed 155mph (limited)

THE ONE TO BUY

BMW Z4 3.0i SE manual, 2003 53 with 40,000 miles. Pay £19,150 from a dealer or £18,250 privately

OR, FOR THE SAME MONEY...

2004 04 Honda S2000 convertible
2003 52 Mercedes SLK 320 Tiptronic 2001 Y Porsche Boxster 2.7
2004 53 Saab 9-3 2.0T Aero convertible
2000 W TVR Griffith 5.0 convertible

VALUES

Autos worth about £1,000 more than equivalent manual version. Estimates based on confidential CAP black book prices. ‘Trade’ is what a dealer would pay to buy your car; ‘Retail’ is what you would pay a dealer