BMW’s UK unit has announced a range of engine and other mechanical updates focused mostly on reduced fuel consumption and CO2 emissions though one upgrade is because diesel SUV buyers asked for more power.

The most popular 5 series model – the 520d – gets a new engine from September with more power but lower fuel consumption and emissions.

The new four-cylinder single-turbocharged powerplant has an output of 177hp, up from 163hp compared to the previous 520d. The zero to 62mph (100km/h) time improves 0.3 seconds to 8.3 seconds and top speed is 144mph.

The model achieves greater fuel economy with a combined 55.4mpg figure. A CO2 emissions figure of 136g/km sees the vehicle drop into band C for UK vehicle excise duty (aka ‘road tax’). The 520d Touring (wagon) has a zero to 62mph time of 8.5 seconds, a combined consumption figure of 53.3mpg and 140g/km emissions.

The new engine is combined with ‘EfficientDynamics’ technology including brake energy regeneration, active aerodynamics, optimum gear shift indicator and low rolling resistance tyres.

The same engine is also going into the X3 SUV range. The X3 2.0d now drinks up to 11% less fuel and its CO2 emissions fall 10% from 191g/km to 172g/km dropping it into tax band E. A zero to 62mph time of 8.9 seconds compares to 10.2 seconds previously, while top speed has increased from 123mph to 128mph.

The X3 2.0d is also now offered with optional six-speed ‘Steptronic’ automatic transmission. So equipped, the model gets 42.2mpg on the combined cycle and posts a 178g/km emissions figure.

Other X3 models also gain EfficientDynamics technology and a consequential improvement in overall performance. The 3.0d and 3.0sd, both see fuel consumption improve by 7% and 11% to 38.2mpg and 36.2mpg respectively on the combined cycle. CO2 emissions on both those models also fall by 7% and 10%. The 3.0sd and 2.5si drop a tier from band G to band F making for a GBP95 annual saving for UK buyers.

All 3-series models – BMW’s biggest selling model range – get the EfficientDynamics package from September in a move that also harmonises engine line-up across all body styles. The technology sees fuel consumption figures improve by up to 24% and CO2 emissions drop by as much as 19% as engine outputs increase by up to 21hp.

The package includes auto start-stop (manual transmission only), brake energy regeneration, active aerodynamics, electric power steering, optimum gear shift indicator and low rolling resistance tyres and was initially launched on the 1 series and 5 series models.

just-auto sampled the technology on a pre-production car last month and found the start-stop system worked almost imperceptibly. All diesel-powered 3s now have standard diesel particulate filters to reduce emissions.

An updated X5 3.0d on sale in October has a revised engine for lower emissions and improved economy. This new X5 is now the only conventionally-powered vehicle in its segment with a CO2 emissions figure that falls below the highest 225g/km banding for vehicle excise duty.

Again, application of EfficientDynamics technology delivers the result. The new model has brake energy regeneration and various needs-only control of ancillary devices. An air-conditioning compressor that decouples from the drivetrain when not in use and air flaps that can close off air flow to the engine to improve aerodynamics when the engine is not at full load are two examples.

All of these features enable the model to produce a CO2 emission figure of 214g/km – a drop of 17g/km compared to the previous model.

The X5 3.0d now qualifies for band F instead of band G duty, saving owners GBP95 a year. Fuel consumption on the combined cycle also improves from 32.5mpg to 34.9mpg, as does acceleration from zero to 62mph – down to 8.1 seconds from 8.3 seconds.

The fuel saving technology has also been applied to the range-topping 4.8-litre petrol and 3.0-litre petrol-engined variants. The X5 3.0si now records an improved combined consumption figure of 27.7mpg compared to 25.9mpg. Emissions have been cut from 260g/km to 244g/km. Meanwhile, the X5 4.8i sees its consumption figure improve from 22.6mpg to 23.5mpg and the CO2 emissions figure drop from 299g/km to 286g/km.

BMW has also added the world’s most powerful production six-cylinder diesel powerplant to its recently redesigned X5.

The X5 3.0sd delivers 286hp and a flat torque curve with a peak of 580Nm from a low 1,750rpm to ensure rapid performance. It can go from zero to 62mph in 7.0 seconds and has a top speed of 146mph.

The drivetrain uses two differently sized turbochargers operating in sequential stages depending on driver inputs. The key to the engine’s smooth power delivery is that, despite the mechanics of two turbochargers providing variable power, they deliver a consistent 2.85bar pressure to the intercooler at all times. One smaller turbocharger provides near instantaneous power at low engine speeds, while a larger turbocharger provides the mid to top end power.

The boost of both turbochargers is regulated by an ECU and three control valves. This arrangement ensures optimum performance delivery from just above idle speed through to the red line and makes for impressive performance figures and an absence of turbo lag.

Power is transmitted via a standard six-speed automatic gearbox and the ‘xDrive’ four-wheel drive system.

Diesel power accounts for more than 90% of X5 sales in the UK and the new X5 3.0sd is being introduced to satisfy the wishes of some existing owners who asked for more performance.

Not to be left out, the entry-level 1-series has set a new benchmark. The 118d now records 62.8mpg on the EC combined cycle and CO2 emissions of 119g/km – putting it into band B – it now costs just £35 a year to tax.

The model also has brake energy regeneration, auto start-stop, electric power steering, low rolling resistance tyres and an optimum gearshift change indicator.