BMW's 3 Series is under siege all of a sudden. Mercedes' brilliant but boring C Class has romped away into the sales lead but the competition from Audi has never really come close to the 3's benchmark dynamics-value-technology mix.

But it's now under fire from both sides as the new A4 has landed in a blaze of appreciation, technical sophistication and sharp pricing. But there's one 3 Series that's safe from direct competition, and it's this one – the turbocharged straight six 340i.

Value

The 3 Series range starts with half the cylinders and capacity in the 318i for $54,900. There's an extra cylinder and 500cc in the $61,900 320i, followed by the $63,800 320d, the $69,900 330i (still 2.0 litres and turbocharged, but more power), $71,900 for the 330e hybrid and finally the $89,900 340i. Being a German company, there's actually about 60 separate models when you add variants, M Sport, wagons and the GT. Then there's the bananas M3 about $50,000 away from the 340i.

The 340i replaced the pre-LCI 335i last year and drops $3000 off the asking price, adding a bit more power and stuff as part of the inevitable mid-life refresh. Part of that refresh saw the entire range receive a reversing camera, 360-degree camera, lane departure warning, heads-up display, front and rear parking sensors and LED headlights in every model, no doubt in anticipation of its updated competitors.

On top of that, the 340i has 19-inch alloys, adaptive dampers, a Harmon Kardon sixteen speaker stereo with USB, Bluetooth and DAB, dual-zone climate control, blinds on rear passenger windows and power rear windscreen blind, keyless entry and start, active cruise control, heated electric front seats with memory, satnav, active automatic headlights, auto wipers, internet connectivity with SIM card, leather trim, auto parking, tyre pressure sensors and wood trim.

The 3 is a fine looking car in profile, with excellent proportions.

Our car had the optional dazzling Opal White leather merino seats and merino leather Individual steering wheel ($2000), sunroof ($2920), metallic paint ($1840), anthracite headliner ($500) and headlight washers ($500), bringing the total to $97,660.

Design

The F30's LCI (Life Cycle Impulse) update didn't bring much to the party visually speaking, despite the impending arrival of a box-fresh A4 and a similar mid-life update from Mercedes. The 3 is a fine looking car in profile, with excellent proportions and familiar glasshouse. A gentle evolution of the E90, it's starting to look its age from the front compared to other cars in the BMW range, but is ageing well. You can pick out the 340i by its dual exhausts, one on each side.

The LED daytime running lights are very distinctive, a pair of bright white spectacles. The Luxury Line is demure, even rolling on 19-inch alloys, to the point of anonymity. That's probably because so many people spend a bit of money on M Sport bits, so if you're after a quiet life, this one is for you.

Inside is as clean and ergonomically sound as ever, with the rotary iDrive controller falling easily to hand behind the gear selector. The dash is clear and simple and visually quite light with stacked materials and colours to break it all up. The ten-inch screen is like a big TV plonked on top of the dash and looks better integrated than the 1 Series' unit.

The front seats in this one are a bit flat-looking but are comfortable once you're in them. They also look quite narrow, so a larger backside might be wanting for support. The rear seats are the best of the three Germans although the middle passenger gets as rough a deal as a C Class's middle rear for footroom.

Cupholders front and rear bring the count to four. The front door pockets don't hold very much and the rears aren't much better. The boot holds 480 litres and there's a ski-port as well as split fold seats.

Safety

Six airbags, ABS, traction and stability control, corner braking control, blind spot sensor, brake assist, lane departure warning, forward collision warning and mitigation. The 3 Series also gets a five star ANCAP safety rating.

Features

BMW's iDrive remains way out in front as the most useable multimedia and entertainment system in any car today. The big rotary dial controller looks after a huge amount of functionality while the widescreen 10-inch screen can be split in two to multi-task.

The Luxury Line car is a lot more relaxed and probably all the better for it

The 16-speaker Harmon Kardon stereo is a belter, with deep rich sound. Connectivity to smartphones is via the central console bin's USB port or Bluetooth and is very easy to set up.

Real-time traffic info is standard and reasonably accurate and if you have a SIM card, you can create a wifi network in the car. There's still no sign of Apple's CarPlay or Google's Android Auto, though.

Engine

The 340i's bonnet houses BMW's new turbo straight six petrol engine. In this guise it produces 240kW and 450Nm, powering the 1540kg 3 to 100km/h in 5.1 seconds. The 340i has 15kW and 50Nm more than the 335i and is almost half a second quicker to 100km/h.

Mated to the ubiquitous 8-speed ZF automatic transmission (you can have a six-speed manual if you like, which is unique in this class), BMW reckons you can use just 6.8L/100km on the combined cycle with the help of stop-start and energy recovery, but we used about 10.4L/100km over the week, mostly in city driving.

Driving

The first thing you notice about the 340i is the effortless feel of the whole package. The power and torque mean you drive with your big toe and your fingertips, with light but direct steering keeping things cool, calm and collected.

Unusually, our test car was bereft of the very popular M Sport package but it did have the adaptive damping. The Luxury Line car is a lot more relaxed and probably all the better for it for more of the time.

The ride and handling balance is a fine compromise, with little of the jiggling we experienced in a recent week with the 330i M Sport. The extra weight of the six-powered car doesn't seem to affect the positive turn-in, probably helped along by the now very well finessed variable ratio steering.