WHEN this car comes to the UK next March it will truly shake up the business car market.

The car in question is the new BMW 320d EfficientDynamics. What makes it so important is this: it's the first premium saloon to dip below the 110g/km barrier.

Why is this so important? Because if you purchase your company cars, you can improve your company's cash flow by claiming a 100% first-year writing down allowance (WDA). Don't worry if you contract hire your company cars – because the leasing company can claim the tax relief and the result will be lower contract hire rentals.

In addition, company car tax will be a measly 13%; and road tax just £35 a year.

The new BMW 320d EfficientDynamics won't be a motoring couch potato, either. Featuring a 163hp 2.0-litre diesel engine emitting just 109g/km CO2, the 320d will accelerate to 62mph in 8.2 seconds. And with fuel economy of 68.9mpg it won't be stopping at the fuel pumps often.

So how has BMW managed to make the 320d EfficientDynamics saloon so tax-efficient and fuel-efficient? There have been changes to the engine construction, lowered suspension, special aero alloy wheels with Michelin EnergySaver tyres, and so on – all in the interests of saving weight and reducing friction.

The 320d EfficientDynamics also comes with the current suite of BMW EfficientDynamics technologies: Auto Start Stop; Brake Energy Regeneration; and Electric Power Steering. These have featured on all four-cylinder BMW 3 Series models since September 2007.

The BMW 320d EfficientDynamics saloon will have a specification similar to the BMW 320d SE. So expect two-zone air-conditioning, rear Park Distance Control, BMW Professional radio, multi-function leather steering wheel and Extended lighting. Although there's no pricing yet, BMW says it will mirror the existing 'standard' BMW 320d SE saloon.

BMW 320d EfficientDynamics saloon - key facts

• Engine 2.0-litre turbo diesel
• Power 163hp
• Torque 360Nm
• Economy 68.9mpg
• CO2 emissions 109g/km
• Company car tax band 13%
• First-year WDA 100%

Further information

Read Mark Sinclair's Special Report Right mix of cars key to green business motoring

For a free factsheet on understanding the new tax rules – such as the 100% WDA for cars under 110g/km – then download it by clicking on this highlighted link The BIG tax change (PDF 518KB).