One is an old favourite, the other a cheeky new character, but the latest Micra city car/supermini and sector-challenging Juke Crossover are both significant arrivals in Nissan showrooms.Together they represent conservatism and creative spirit embodied in two models which will play significant roles in Nissan's sales ambitions for 2011.In 2010 Nissan's UK new car sales showed a 15% improvement over 2009. Of the 89,681 new cars sold last year, 39,000 of them were Qashqai crossovers.Juke production in Sunderland has replaced that of the Micra, which is now being built and supplied to the UK from India after some 30 years of production and 5.65m sales worldwide for the model.The latest Micra has a completely new platform underneath as well as body on top but it retains some acknowledgements to the previous series inside and out, most notably the very generous room, neat proportions and simple powertrain and chassis.All engines are three-cylinder 1.2 units with launch models of 79bhp and the summer will see the arrival of a supercharged 96bhp, both petrol, with very low emissions and high economy normally only seen in a diesel, which will not be available in the new fourth generation Micra. They all exceed 50mpg average consumption.Two engines with choice of five-speed manual or CVT transmission share the same five-door body and Visia, Acenta and Tekna trim levels with standard power steering, six airbags, electric front windows, Bluetooth and ESP.Acenta comes with alloys, climate and cruise control and Tekna get the Connect navigation and entertainment system, large sunroof and parking slot assessment system, automatic headlights and wipers, folding mirrors and drive computer.The new Micra is longer, wider and lower than the previous generation with significant additional room in the passenger compartment but it has stayed true to its design features and gives very good all round vision with big windows, low waistline and slim roof pillars.With 70% of Micra sales expected to come from private buyers, Nissan has decided to introduce a zero per cent loyalty rate for existing Nissan owners to purchase the new model and prices are between £9,250 and £12,350.For the new series, which is not only more economical and cleaner than the outgoing version, the insurance groupings are substantially less as well so the overall cost of ownership will be much lower.It is expected about 20% of Nissan Micra buyers will select the CVT automatic version of this city car, and it is the better choice of the two transmissions. Selection is simple, changes creamy and there is adequate power for the job in hand.What is possibly more important is that left to its own devices the transmission keeps down the engine noise level experienced with the manual model tested as well.The three-cylinder engine is always going to sound busy, but it is more muted when matched to the CVT unless you rush along. The manual lets you know it's working away getting the most out of the engine.For some unknown reason, the road noise also seemed more noticeable in the manual and, despite its refined equipment, it was not particularly sophisticated in the suspension department - and you not only heard but felt bumps and potholes. Nissan Micra MILESTONES Nissan Micra 1.2-litre, 5-Door City CarPrices: £9,250 to £12,350Engine/transmission: 1.2-litre, three-cylinder, petrol, 79bhp, 81lb ft of torque, 5-speed manual or CVT auto optionPerformance: 106mph, 0-62mph13.7 seconds, 56.9mpg CO2 115g/km, VED road tax £0 First Year rate then £30 per annum, 10% BIK company car taxInsurance group: 7For: Cheerful styling, cheap to buy and to runAgainst: Engine sounds busy, road noise intrusion, only adequate suspension performance