I HAVE seen some strange, quirky and cutting edge features on new cars, but I have never found a secret button on a tail light or a dash that lights up like the Knight Rider KITT car.

Overhauling your most successful model is either brave or barmy - especially when you have sold 1.9 million cars. But the new Mazda 3 is even more powerful, more luxurious and more stylish than the old one.

The quirky features include the centre console lighting up like a Christmas tree when any of the audio or climate controls are touched or changed. The clever blue lighting acknowledges that the command has been received.

The other  feature is the small rubber button in the centre of the rear light, which I first thought was dirt. When you push it (with the car transponder in your hand) it unlocks all of the doors.

Clever, but it's biggest selling point is that you get all that and a lot more and it's cheap to run.

It takes its exterior styling cues  from the new Mazda 6 and the Mazda2. With the trademark grilles, powerful shoulders and a sporty but still subtle body kit the 3 is a striking car.

The full line up of engine and trim levels is bewildering. There are 15 different trims and seven different engines, starting at the 1.6-litre petrol model and going right up to a turbo charged 2.2-litre diesel taken off the Mazda 6.

This packs a huge amount of punch, is nicely refined and claims to average a whopping 52.3mpg, a figure that seemed optimistic on the test drive.

For better economy, the new ‘i-stop' system restarts the engine in just 0.35 seconds - roughly half the time of conventional stop-start systems. Mazda says it cuts emissions and consumption by 14 per cent.

I took the 3 on a fairly long motorway cruise and whilst it appeared to be fairly frugal, it didn't hit the heights of the claimed 50-plus mpg. The balance was a tough one to strike between letting the 2.2-litre loose or getting the best economy which came, naturally, with sedate and steady motorway driving.

The best balance between sporty performance and saving money is the 1.6-litre diesel that boasts CO2 emissions below the ultra-efficient benchmark of 120g/km, which qualifies it for £35 road tax. For company car drivers it means that it fits into the lowest 13 per cent benefit-in-kind tax bracket.

But it's hard not to want to get the best from the 3's sporty attributes. The steering is responsive, cornering grip is excellent and it's fun to drive. The ride is firm, but not uncomfortable. And as speed increases, things smooth out.

Road noise is noticeable, but the diesel engine is in itself very quiet and refined.

The cabin has a reassuring feeling of quality, comfort and luxury. There is decent room for everyone and plenty of adjustment for the driver. Even the boot is surprisingly big for a hatchback, bigger than some saloon cars.

The interior styling has been pinched from the bigger an more expensive Mazda 6 - which is no bad thing.

The hub of the dash is the MID, or multi information display unit, which displays the trip computer and audio system and is controlled by buttons on the multi-function steering wheel.

Every model is generously equipped and some of the specification on the Sport model is bordering on those inside luxury cars.

Even the entry-level models get air-conditioning and electric front windows. This car model had a six CD dashboard changer, cruise control, heated seats, and Bluetooth phone connection. It also has clever dusk-sensing automatic lights and rain-sensing automatic wipers, a smart entry system and a Bose sound system with ten speakers.

The sport styling kit is what really sets it apart and it includes 17-inch alloys, bucket sport seats, tinted rear windows, low skirts, front and rear sport bumpers, dashes of chrome, a sports exhaust and large rear spoiler.

The levels of safety kit is also class-leading and includes dynamic stability control, anti-lock braking system, electronic brakeforce distribution, traction control system, active headrests and six airbags as standard. The 3 also has an alarm, immobiliser and deadlocks as standard.

The only negative is the same one I have with almost every new hatchback. The vision through the narrow side windows, tiny wing mirrors and small rear window can make it tricky to manoeuvre and this is a surprisingly long car.