CHANGES to form and function are coming on stream at Volvo as the Swedish car maker introduces the latest versions of its big S90 and V90 saloon and estate cars.

Sporty new R-Design derivatives are being added to both line ups while a heavy duty Cross Country model is arriving in the V90 range.

The R-Design cars are priced from £35,455 for the S90 and £37,455 for the V90 putting them mid-range between Momentum and top grade Inscription specification.

More powerful D5 versions which come with Volvo's PowerPulse turbo diesel engines cost from £41,955 and £43,955 while the all-wheel-drive V90 Cross Country is priced from £39,785 for the D4 and £43,585 for the 235bhp D5.

The additions complete Volvo's new 90 series array of large cars which began with the launch of the XC90 SUV in 2014 - the car which went on to be dubbed the safest vehicle in the world.

Safety remains paramount in the Volvo camp and the new cars have just become the first to achieve a top score in the latest Euro NCAP automatic brake tests in relation to pedestrians.

Sprucing up the S90 and V90 with the R-Design treatment is more than cosmetic and both cars get suspension tweaks as well as a reduced ride height, sitting more than half an inch lower than the regular models.

The result is improved feel and the V90 we tried with the 190bhp D4 2.0-litre Drive-E diesel was nicely agile yet retained all its ride comfort.

Performance is the same as the other V90 D4s with a lively 0 to 60 time of 8.5 seconds, a top speed of 140mph and emissions of 119g/km giving it an official fuel return of 62.8mpg although we could muster only 46 to the gallon.

But it's on the style side where the R-Design set up has the most impact with gloss black body trimmings, a shiny grille, matt silver door mirrors and larger front air intakes.

Inside, there are other upgrades including a 12.3-inch TFT instrument panel - larger than that of fitted to the rest of the range - perforated leather on the steering wheel, sports seats and honeycomb metal trim.

It all adds a touch of dare and both saloon and estate carry a mean air.

More significant is the impact of the Cross Country V90 which looks much more rugged than its conventional stablemates.

With added body protection around the wheel arches, skid plates front and rear, bigger door mirrors and a diamond studded effect to the grille plus the V90 Cross Country has plenty of road presence.

It also sits more than two inches higher than a normal V90 and the added ground clearance helps make it a competent soft-roader.

The powerful D5 version has plenty of guts on and off the road and Volvo's PowerPulse turbo system gives it a hefty punch slashing its acceleration time to 7.2 seconds.

It works by blasting a shot of compressed air into the turbo to spool up the turbines and eliminate so-called turbo-lag under acceleration.

As such the car has real bite without much impact on economy or emissions. Official figures are 129g/km and 57.6mpg although the real world performance returned an average of 37 to the gallon.

For off-road purposes Volvo is shodding the 18-inch alloys on the Cross Country with super-grippy tyres and has remapped the powertrain software, adding an extra mode to the drive selections for optimum traction.

Once engaged it locks the car in low gears at speeds of up to 25mph and enables hill descent control. There is also a hill holder device for keeping the car in check on gradients.

The combination works well and the V90 Cross Country made a fine fist of some muddy, rutted forest tracks taking all in its stride without issue.

Exceed the off-road mode speed and the V90 reverts automatically to its comfort setting and there is little fuss involved controlling the vehicle.

Neither was it unduly thirsty when asked to perform under such conditions and even though the four-wheel-drive set up was working hard fuel economy slipped only to 26 to the gallon after a good mud-plugging session.

It is 20 years since Volvo first introduced Cross Country models - the original was an 850 - and they have found a niche with those who need an estate car for all seasons.

The new model comes with all of the 90 series models' safety and luxury features which include large animal detection devices, run off mitigation should the vehicle leave the road and Volvo's Pilot Assist semi-autonomous drive system which allows the vehicle almost to drive itself while motorway cruising.

The classy looking Sensus touchscreen display that is standard fit on all S90 and V90s has been updated and now allows for Android Auto connectivity as well as Apple CarPlay.

However, there are still options to be had and the V90 D5 Cross Country we sampled included a Bowers & Wilkins premium hi-fi, active air suspension and a 360 degree camera system (useful when tackling the forest tracks) which took the price of this particular model up to £56,485.

Nevertheless, all of Volvo's big cars are premium offerings which are out of the top drawer on all fronts. The new additions of R-Design and Cross Country standards can only embellish that reputation.