Less than year from its UK launch, Infiniti can go for growth now diesel power has arrived.The premium brand of Nissan came to the UK market in October 2009 with a small range of petrol powered saloon, coupe and SUV models and just one sales centre, in Reading.Now it has opened another in Piccadilly, London and will be rolling out more on the back of new diesel powered FX and EX SUV models it has also added to the range this month.Sales centres will open in Birmingham in September and the following month in Glasgow while 2011 is expected to see developments in Stockport, Leeds, West London and possibly Bristol.The diesels will be significant models for the Infiniti range which began sales in America twenty years ago and where petrol engines dominate. But now Infiniti is looking for future growth throughout Europe with its first diesels after commencing petrol model sales in 2008.Infiniti believe that the UK market will be its best in Western Europe. It expects to sell 400 cars in Britain before the end of March 2011 but over five years to grow this to about 9,000 sales when a projected 12 centres are fully operational and a full range of hybrid models are also available.Key to growth is the introduction of the diesels this autumn and they will change the buying patterns seen so far, says Infiniti global communications director Wayne Bruce.'About 55% of our sales have been the FX full size 4x4 which has become the iconic model for the brand and which everyone identifies. But as the brand becomes more established we are seeing increasing orders for the EX compact 4x4 SUV series.''With the arrival of the diesel engine it will also give a lift to the EX and the FX from customers who particularly want a diesel for economy and who still want a sporting drive delivered by Infiniti.'He said that since UK sales started the predominant brand part-exchanged by customers was BMW. There have been few premium Japanese Lexus models put in exchange because Infiniti appealed to a younger driver than Lexus and newcomers to the brand were closer in age to the average BMW owner.As sales grow, Mr Bruce said he believed company or fleet sales would rise to take half the business when the market could appreciate their rarity and residual value based on quality and equipment. Infiniti EX and FX diesel SUVsThe new 238PS 3.0-litre, V6 diesel and 7-speed automatic gearbox is a Renault-Nissan group product specifically tuned and tailored for its Infiniti models. It has intelligent all wheel drive and depending on model emits 224gkm in the EX series or 238gkm in the FX models.Prices are comparable to the petrol equivalents. The new engine joins the familiar line up of models and their Standard or GT trims in EX and the GT or S versions of the FX.Premium upgrades are available on all versions and the EX GT Premium includes active lane departure prevention, which senses when a car is drifting across the road and gently directs it back to the centre of the lane it is travelling in. It was previously available only in the FX. Infiniti FX diesel first driveThe FX 3.0d diesel full sized 4x4 sporty SUV, tested in S Premium trim at £51,730 is definitely the edgier of the two models. Its most obvious competitors are the BMW X6, Range Rover Sport and Porsche Cayenne.It shares the engine and gearbox with the EX 4x4 compact SUV but Infiniti's Cranfield engineers in the UK have been listening to customers and tuned the suspension and transmission to be sharper and greater dynamically focused than the more rounded EX.With column paddles not found on the EX, the FX is more responsive behind the wheel even if to some it is appreciably harder riding even with the air suspension set to the auto mode rather than sport characteristics. I actually found little difference in ride quality between the two settings over a short test route. Infiniti FX performancePerformance is good from rest, through the gears and composed on the motorway with low noise levels and a pleasant exhaust note. I managed to average about 26mpg overall.In the £41,220 EX30d GT Premium compact SUV 4x4 the ride is set and definitely much softer than its stablemate. Performance is good, though not exceptional and I eased it towards 28mpg overall.Testing the LDP (Lane Departure Programme) system is a little unnerving but it works very well, sounding a beep before activating the brakes and bringing it back to the centre of the lane irrespective of which way you are wandering. I just wondered when such systems will find their way onto more bread-and-butter reps cars.Ride quality is softer and more agreeable for cross country journeys and you still have the ability under-hand to select a manual drive mode for the transmission if you wish to use it instead of full automatic. It steers and brakes very well.The EX and FX are good four seaters, but you might find three in the back a tight fit, particularly if they were tall and wanted headroom in the FX. Infiniti FX MILESTONES FX 3.0d 4x4 SUV S Premium. Price: £51,730.Engine/transmission: 3.0-litre, V6, turbodiesel 235bhp, 406lb ft (550Nm) of torque from 1,750rpm, 7-speed, automatic, 4x4 drive.Performance: 132mph, 0-62mph 8.3 seconds, 31.4mpg (26mpg on test), CO2 238g/km, VED road tax £750 First Year rate then £425 second year onwards, BIK company car tax 35%.Insurance group: 47.For: Stylish, bold sports 4x4, rarity value, punchy diesel engine lowers running costs a little, well equipped.Against: Not that roomy or classy, still incurs high levels of tax, unknown residual values.