BMWBMW is busily not only developing all-new cars such as the new M3 Saloon and M4 Coupe, but also improving the ones already on sale in its showrooms.

The latest model year changes are extensive and wide-ranging: here, we take you though them all and outline why it may be worth waiting before you sign on the dotted line…

190hp 2.0-litre diesel for BMW 520d

A year on from its midlife refresh, the BMW 5 Series will receive the new generation four-cylinder diesel engines this summer, with the headline act being the new 190hp 520d. Torque is up from 280 to 295lb ft, yet emissions for the 520d saloon are rated between 109 and 124g/km.

The 2.0-litre diesel engine, which is also available as a 150hp variant in the 518d, features an aluminium crankcase with thermally jointed liners, integrated balance shafts and a map-controlled oil pump.

The 518d saloon will accelerate to 62mph in 9.5 seconds, with the 520d saloon getting there quicker in just 7.9 seconds. In both cases, the Touring variants are marginally slower.

Also available with the twin-turbo diesel engine will be the xDrive four-wheel drive system, which sees emissions rise to between 124 and 134g/km for the saloon and 133 and 143g/km for the estate.

xDrive to premiere in the BMW 2 Series

Rather fittingly, the 2 Series range is to receive two new additions this summer, with the arrival of the M235i xDrive Coupe and the 228i Coupe.

The xDrive four-wheel system will enable drivers to get every last drop of the 326hp from the six-cylinder M235i engine transferred to the asphalt, helping the artist formerly known as the 1 Series Coupe achieve a 0-62mph time of 4.6 seconds.

Yet despite this level of performance, the M235i Coupe will still be able to achieve a claimed 36.2mpg on a combined cycle, whilst emitting just 182g/km CO2. The eight-speed Steptronic transmission is fitted as standard.

Buyers looking for greater efficiency in exchange for a drop in performance might look towards the new 228i Coupe. Its four-cylinder 2.0-litre petrol engine delivers 245hp and will accelerate to 62mph in 5.7 seconds.

Fuel economy is quoted at 42.8mpg, with CO2 emissions of 154g/km.

Nine engines available for the BMW 4 Series Convertible

The number of engines available in the BMW 4 Series Convertible increases from five to nine this summer, which includes the introduction of a new 420i entry model.

The 2.0-litre twin-turbo petrol engine delivers 184hp and 199lb ft of torque, whilst emitting between 154 and 159g/km.

At the opposite end of the spectrum, the Autobahn-storming 435i Convertible will also be available with the xDrive four-wheel drive system. The 306hp petrol engine offers between 34.9 and 35.8mpg on a combined cycle.

The 4 Series Convertible range also boasts an extra three diesel engines, in the shape of the 218hp 425d, the 258hp 430d and the 313hp 435d xDrive.

Wholesale changes to BMW 4 Series Gran Coupe line-up

Not to be left out, the 4 Series Gran Coupe gains five additional variants, four of which include the xDrive four-wheel drive system.

These include the 184hp 420i xDrive Gran Coupe and the 306hp 435i xDrive Gran Coupe, both of which are petrol engines.

Three six-cylinder diesel variants will also be available, including a 258hp 430d and 430d xDrive, as well as the most powerful diesel engine in the range – the 313hp 435d xDrive Gran Coupe.

Wider availability of eight-speed Steptronic transmission

BMW’s new eight-speed transmission will be available on the 1 Series, 2 Series, 3 Series, 4 Series and 5 Series.

On vehicles equipped with satellite navigation, the proactive drive system will adapt to changing situations, optimising gearshifts for roundabouts and bends. It will even optimise the up-shifts for accelerating out of bends.

Several variants of the BMW X5 will be offered with the Steptronic transmission as standard, with BMW promising “new standards in performance and efficiency” within the segment.

And that’s not all…

Other changes for the summer include tweaks to BMW’s Business navigation system and the Professional radio unit. BMW claims the graphics will generate 10 times faster and include new 3D elements and animations.

All model variants of the 5 Series Gran Turismo will feature Dakota leather trim as standard, with the 3 Series now boasting speed-sensitive steering across the range.

The final introduction of note is the arrival of the new BMW 7 Series Edition Exclusive. As the name suggests, this ultra-luxurious 7 Series includes metallic paint, 19-inch alloy wheels, an enhanced Nappa leather trim and an instrument panel finished in leather.

BMW hasn’t revealed the prices of its new products, but they are all expected to launch in the summer.