BMW: Aspirational and eco-friendly

BMW's Series 1 convertible will feature the thirst-cutting EfficientDynamics tech. Photo / Jacqui Madelin

BMW can boast all it likes that EfficientDynamics tech will save fuel without compromising performance. But is that true in real-world driving? Instead of awaiting its October New Zealand arrival in a range of cars, we borrowed a BMW 123d MSport convertible in the UK to find out.

What's new

Not the 1 Series convertible, but the fuel-saving tech that it sports. EfficientDynamics encompasses a range of interventions that will, in various combinations, be available here.

This 1 Series convertible features auto start-stop, brake-energy regeneration, electric power steering with servotronic, intelligent alternator control and optimum gearshift indicator.

The company line

EfficientDynamics will cut fuel consumption without affecting performance. BMW NZ says the current 123d cabrio delivers an overall thirst of 6.2l/100km and CO2 emissions of 164g. It says the new model, with its EfficientDynamics bits, drinks at 5.4l/100km and emits CO2 at 144g, while engine output remains identical.

BMW says EfficientDynamics will substantially reduce fuel use and carbon emissions across its range.

What we say

In fact my UK test car drank at a rate of 6.5l/100km. But while the overall figure assumes a substantial amount of time is spent at open-road pace, my UK drives rarely delivered highway driving. Most time was spent on urban roads, or flooring it for the decent torque boost on short stretches of rural routes. Such driving patterns are not a recipe for frugality, so this figure's an achievement - especially since there appeared to be no downside.

On the road

Frankly, the only EfficientDynamics intervention you'll notice is the stop-start. Haul up at lights in neutral, and as soon as the clutch releases, the engine dies. Depress the clutch, and she starts. Only once was the car confused - when I pulled up at a red light just as it changed and the car was killing the engine as I depressed the clutch, causing a bit of a lurch. Otherwise you get used to it, and the fact you don't need to switch off when you arrive - the car does it for you.

I found the diesel's sweet spot so obvious I didn't need the gear-change reminder. Stuff like brake regeneration which harnesses engine power otherwise lost during over-run or braking to reduce alternator use, or the flaps that close behind the grille to improve aerodynamics when the engine needs less air, aren't something you'd notice, so the fuel saving is effortless.

Why you'll buy one

A smart, sweet-handling aspirational car with eco-friendly overtones. That it is also a reasonable proposition as a daily-driver is a bonus.

It's a two-plus-two rather than an efficient four-seater but proved easy to live with, the torquey engine strong at low revs, and still capable of lifting the pace at NZ's open road limit.

Why you won't

There are cheaper ways of saving fuel, or you don't want a BMW. If you do, EfficientDynamics will soon be a part of the package regardless.