Overview

The BMW Z4 was launched in 2003 as a fresh rival for the ever-popular Porsche Boxster and the replacement for the more style-focused Z3. The Z4 E85 is now a very affordable used car, too. Prices start from around £3,000, making it almost £5,000 less than a Boxster of the same vintage. But is the Z4 worth taking a punt on? Or would you be better off with the crowd-favourite Porsche Boxster?

BMW certainly got the Z4’s basics right. It’s front-engined, rear-driven chassis still has what it takes to thrill you on your favourite back road – and its looks and interior stand up to today’s scrutiny. The Z4 also has a super-fast convertible electric roof that can be retracted in just 10 seconds. In a country with weather patterns as unpredictable as Britain, that’s worth its weight in gold.

Unlike its predecessor, BMW also sold the Z4 E85 with a proper range of engines. The most basic Z3s left the factory with asthmatic 1.8 and 1.9-litre engines, but BMW dumped those in the scrap bin when it was designing the Z4. The least powerful engine available is a 150bhp 2.0-litre four-cylinder petrol unit which, crucially, provides enough performance to make the Z4 feel like a true sports car.

If you really want to set your pulse racing, though, there are two straight-six petrol engines to choose from. The 2.5-litre version has 192bhp, while the fastest 3.0-litre unit serves up 265bhp. For the best results, make sure you find a car fitted with a manual gearbox. It adds to the driving experience.

BMW Z4 known faults and common problems

The earliest BMW Z4s are now 20 years old. Some have passed through half a dozen owners already – and the most unloved examples can suffer from a range of mechanical and electrical problems. But, because the Z4’s devout enthusiast scene has had two decades to pinpoint the car’s weaknesses, we have a great picture of its most common failure points.

If you can find a well-maintained example, the problems you’ll face will be much less serious. Most of the Z4’s issues are caused by the previous owner’s unwillingness to replace perishable components. However, there are some trickier known faults with the car’s electric folding roof and brake lines. Scroll down to learn more about the Z4’s foibles so you can enter a purchase with confidence.

Buying guide

Common issues and what to look for if you’re looking at getting one

1. BROKEN REAR SPRINGS

The Z4’s rear springs are notorious for snapping. It’s normally the coils on the end of the spring that break – and you’ll need to replace both to fix the problem correctly. To further complicate matters, it’s a difficult problem to diagnose without getting the car on a hoist. Take the car on test drive to check whether the handling feels baggy or stand back and inspect its stance. If the car’s rear end is squatting on the tarmac, there’s a chance the springs have failed.

2. RUSTY BRAKE LINES

The Z4’s brake lines are prone to rotting. If left unchecked, they could eventually develop a hole which will allow the brake fluid to leak out. That means you won’t be able to stop. If you can, get under the car and give the brake lines a good poke, concentrating on those at the rear. If you can pull flakes of rust off them, proceed with caution. Replace them as soon as possible and protect them with some paint or some spray grease to keep the moisture and road salt at bay.

3. ROOF MOTORS

The water drains near the Z4’s roof motor often get blocked with leaves and foliage. That allows water to build up in the cavity around the motor, which eventually short circuits the motor and prevents you from lowering the car’s roof. And the problem’s a real pain to fix because, to do the job right, you need to remove the soft top.

There are other solutions. Some owners have managed to change the motor with the roof in situ (which looks like a rear knuckle scraper of a job), while others have eliminated the problem by moving the motor from its original location behind the passenger door to the boot. If the car you’re viewing has this problem, only buy it if you’re confident on the tools.

4. HAZY HEADLAMPS

The BMW Z4’s headlamp lenses are particularly prone to hazing with road grime. The effect can be downright dangerous, too, as it severely limits your night-time visibility. You can fix the problem by polishing the lenses with a headlight restoration kit, but lots of owners simply swap their standard halogen light units for the upgraded Xenon units fitted to more expensive versions of the car.

5. FLIGHTY DOOR MIRROR GLASS

The sealant holding the Z4’s door mirror glass in place loses it adhesion over time. Eventually, the glass will drop off the frame and, if you’re unlucky, smash on the tarmac. Give your potential car’s mirrors a good wobble. If they seem loose, remove them and apply some fresh glue.

6. WINDOW MECHANISMS

These just wear out over time. Try the windows on the test drive. If you hear a scraping sound in the door as the window moves through its stroke, the regulator cables are on their way out. They glass often gets stuck in the down position, too, which presents a serious security problem for your car. Owners recommend to not buy a repair kit. Buy either a new regulator or a good used one and replace the entire unit.

7. WIPER MOTORS

If your Z4’s wipers aren’t working, there’ll probably be a fault with its wiper motor. Don’t rush out and buy a replacement one, though. You might be able to fix the problem by cleaning the one you have. You need to dismantle the trims on your car’s scuttle, remove your wiper motor, pull off its rear cover plate and clean off the grease that has built up on the metal electric contact strip. The grease completes the circuit which prevents your wipers from moving. You can find detailed guides on how to do the job on several BMW Z4 owners forums.

8. POORLY ADJUSTED HANDBRAKES

The Z4’s handbrake cables stretch over time, like any other car. If the handbrake lever of your potential purchase is unusually vertical when engaged (if it takes 10 clicks or more to reach the end of its travel), you’ll need to adjust the cables to make the handbrake easier to operate. You’ll need to get the car off the ground and make the adjustments at the rear hubs.

9. BROKEN EXHAUST HANGERS

Road vibrations fatigue the welds that hold the Z4’s exhaust hangers in place. They eventually snap and allow your exhaust system to rattle around freely under the car and make some very alarming noises. It’s an easy fix, though. All you need to do is weld the hanger back onto the exhaust. The only slight problem is that the Z4’s exhaust system is made from stainless steel, so you need to be a competent welder to get a good finish.

10. MISFIRING ENGINE

The four-cylinder BMW Z4 has a valve in its intake system that controls the flow of air into the engine. It’s called a DISA valve and it’s basically a big plastic flap that changes the length of the intake runners to improve performance depending on engine speed. The value is also known to break – and when it does, your engine will run like a bag of spanners. You might also hear a worrying rattle from under the bonnet.

What models and trims can you buy?

BMW kept the Z4’s line-up refreshingly simple. The car was only ever sold in three mainstream specifications and two special editions called Edition Sport and Edition Exclusive. For the main trims, there’s the base-model, the SE and the Sport. The most basic Z4 is notoriously spartan inside, featuring only a couple of creature comforts such as climate control and CD player.

The middling SE model gained extras such as front fog lights and heated door mirrors, while the Sport model received part-leather seat upholstery, aluminium interior trim and a racier suspension setup. Most of the Z4’s equipment was optional, though. Its options list included items such as metallic paint, electric seats, cruise control, headlamp washers and parking sensors.

Over the next few pages, we’ll review each aspect of the Mk1 BMW Z4, considering it practicality, comfort, fuel economy and driving experience. We’ll then off our final verdict on the car and let you know whether it’s a recommendable used car.