HOW boring the world would be without the great rivalries. Tiger vs Ernie. Britney vs Christina. Bush vs everyone else. Mercedes- Benz vs BMW. And, to get more specific now, E-Class vs 5 Series. If you want to start a motoring debate, mention these two and the talk will be heated. We crowned the E-Class the best executive saloon in our annual Top 12 awards, and many readers were up in arms. What they missed was the fact that the award went to the Mercedes as a range, as we had only tested one example of the 5 Series up to that point, the 530d. BMW had yet to show its trump cards. Here they are.

Launched simultaneously, the new 545i is the flagship (until the arrival late next year of the M5) and the 525i functions as the entry-ticket to 5 Series motoring. At first glance the two are hard to tell apart, a matter not helped by our 525i arriving with non-standard wheels. That left the chrome on the 545i’s grille and slightly different exhaust outlets as the only differentiating factors.

Most of our testers have now warmed to the Five’s styling, but some still have reservations – mostly about the slashes that make the rear three-quarter view look odd. But there can be little doubt that the BMW is the most visually arresting car in its class. It is, however, an amazingly light and angle sensitive design – by moving around it, and varying your height, the Five can look either fantastic or odd.

The cabin is taking somewhat longer to win us over. The basic architecture is pure 7 Series. All 5 Series models feature iDrive, with the characteristic second binnacle on top of the hangdown section housing the display screen, and the silver rotary knob (controller) on the centre console. Much has been said about iDrive, so we won’t go into detail again here, except to say that the addition of the “menu” button just below the controller has been a very worthwhile improvement – you no longer end up jumping from one screen to the next in a frustrated effort to get back to the “start” screen.

Normal rotary knobs for the climate control system are located on the hangdown section and are simple to use. All 5 Series models have a front-loader CD player. Volume can be adjusted either by using the remote buttons on the steering wheel or the small volume knob next to the CD slot. Ergonomically speaking, the new facia design initially appears a little confusing, but if you’ve bought one, you will no doubt spend enough time behind the wheel to figure it out satisfactorily.

The 545i comes with “Comfort” seats that feature electrical adjustment in every direction (the top-half of the backrest can be individually adjusted), and memory for the driver’s chair. Our car also had the optional heating, ventilation (excellent) and massaging features fitted. Although a little harder than those in an E-Class, for example, the BMW seats are superb, providing a very good balance of comfort and support. The 525i’s seats offer fewer adjustment options, but were regarded as impressively comfortable by the majority of our testers.

Rear legroom has been improved over the previous Five by 46 mm, the result of a 62 mm longer wheelbase. Although the car can accommodate three people in the back, it is essentially tailored for two. A big armrest folds out of the middle of the backrest, and houses two drink holders and a storage facility. The backrest itself cannot be split or folded forward, leaving all luggage carrying duties to the 392 dm3 boot.

Cabin quality is very good, save for one or two areas, such as the ventilation outlets, which look a little out-of-place compared with the rest of the car, and the rickety drink holders that slide out of the facia.

The 545i comes with almost all the bells and whistles. Besides the usual features, it also gets rain sensors, 6-disc CD changer in the boot, Servotronic speed related power steering, Active front steering, headlamp washer system and adaptive headlights. But you pay extra for items such as park distance control and a base navigation system.

The 525i is not a stripped-out variant of the 5 Series. You still get Dakota leather upholstery, electric height-adjustment for the driver’s seat, front-loading radio/CD player, multifunction steering wheel, dual front, side and rear airbags, automatic air-conditioning and cruise control as standard, amongst other things. Active steering (R12 500), xenon headlamps (R8 500) and a six-disc CD changer (R4 000) are some items on the vast options list. Our test unit was fitted with optional 225/50 17-inch run-flat tyres (16 inch 225/55 non run-flat tyre are standard).

One surprising omission applicable to both cars is the lack of seatbelt height-adjustment.

The 545i is powered by BMW’s acclaimed 4,4-litre V8 engine that features Valvetronic, a fully-variable intake manifold, and bi-Vanos. It develops a meaty 245 kW at 6 100 r/min and 450 N.m of torque at 3 600. More than 80 per cent of the maximum torque is available between 1 500 and 6 400 r/min.

Both our test cars came equipped with the six-speed Steptronic transmission. Six-speed manual or SMG transmissions are available on both. Gearshifts are quick and smooth, and by knocking the lever to the left, the Sport function is activated, resulting in quicker downshifts when the throttle pedal is pushed down with purpose. As an aside, BMW also seems to have eliminated the annoying 1st gear “thump” that was evident on our previous 530d test car.

With the traction and stability control systems deactivated, the 545i’s Dunlops (245/45 are standard) were sent spinning on our test strip – lurid tail slides and smoky burnouts are available on demand, if you wish. We achieved a best 0-100 km/h time of 6,14 seconds and a 247 km/h (limited) top speed. Overtaking acceleration is ferocious, the 545i needing only 2,46 seconds to get from 120 to 140 km/h.

If you’re in the market for a car like this, fuel economy is unlikely to be the main concern, but for the record, the 545i’s fuel index figure worked out at 13,19 litres/100 km, which is perhaps slightly more than we had expected, but not by much.

The braking system consists of inner-ventilated discs all-round, measuring 324 mm in front and 320 mm at the rear. BMW’s latest DSC III (Dynamic Stability Control) is standard on both models. This system integrates ABS, ASC, DBC and EBV. Both cars performed very well in our emergency braking test routine, the 525i scoring the better 2,83 second average, with the 545i not far behind on 2,93.

The 525i’s 2,5-litre straight-six delivers 141 kW at 6 000 r/min and 245 N.m of torque at 3 500. We were slightly disappointed by the 525i’s acceleration figures. The 9,61 seconds 0-100 km/h time does not do justice to an engine that feels so responsive in general driving. Overtaking acceleration times are more indicative of the engine’s true nature. Steptronic is a good match for the smaller engine – there’s little hunting, and shifts are quick. The 525i’s fuel index figure worked out at a competitive 11,15 litres/100 km, or 8,97 km per litre.

Suspension design is typically BMW – MacPherson struts in front and multi-link at the rear. The front suspension is made almost entirely of aluminium, and a subframe accommodates the steering, transmission, anti-roll bar, trackcontrol arms and tie-bars. The rear axle features four control bars that are mounted on a subframe that also carries the differential. Our 545i came fitted with the optional Dynamic Drive active suspension that counters body roll during cornering. Dynamic Drive is made up of two active anti-roll bars, a valve block with integrated sensors, a dual oil pump, an accelerometer, a control unit and additional supply components.T he key elements are the two active anti-roll bars taking the place of conventional, mechanical roll bars on the front and rear axles. Active steering (varies the steering ratio according to road speed) is standard on the 545i and optional on the 525i.

Enthusiastic drivers will be relieved to hear that all the technogadgetry has not blunted the dynamics. But let’s get the one or two little niggles out of the way first. At city driving speeds, the ride can be a little too harsh, with rippled road surfaces especially upsetting the car’s trademark composure. But once the speed picks up, and on any other road surface, the Five’s ride can’t really be faulted. Active steering, too, has its ups (great for parking) and downs (not so good at highway cruising, where steering feel is too light off centre). But that’s it.

We would say the E-Class remains the more comfortable cruiser, but drivers who take the wheel for the sheer sense of enjoyment are likely to be more impressed by the Five. The steering is scalpel-sharp when cornering becomes “enthusiastic”. The Five goes exactly where you point it. And the rest of the car remains remarkably composed no matter how sudden the direction change. Driving aids provide the necessary safety net without spoiling the fun and allow for a significant amount of sliding to take place before gently bringing matters under control. As we’ve said before, switch these systems off and you’ll very much be a master of your own destiny. With so much power (in the case of the 545i) going to the rear wheels, you’ll need to be quick to catch it when it lets go. The overriding impression is one of a car that has been meticulously honed – it feels solid, yet light on its feet, fast, but not wayward, refined, yet still thrilling.

Test summary
For the enthusiastic driver, the 5 Series is unmatched in its class. Some of the technologies may take some getting used to, but the basics are right. The Five grips, steers and corners like no other car in this class. Dynamically, it leaves the competition trailing, and the thrilling dynamics are backed by superb engines and a spacious, comfortable and luxurious cabin… but one that is perhaps not always easy on the eye. For the more traditional executive saloon buyer, the firm ride may perhaps be a problem, and for them the E-Class represents an excellent alternative. In the minds of the public the rivalry will continue, but all the tested Fives have been adjudged better than their respective rivals. Consider the tables turned…