What is Audi S line? It's a question you'll doubtless have asked yourself if you've ever stuck a tentative toe into the shallow end of the Audi configurator, so what exactly is it?

Well, S line is a trim level that's available through the range from the entry-level A1 to the range-topping A8, which gives you the cache of a sporty model – a subtle body kit, big rims and some sporty interior appendages – without having to cough up for a proper sporty model with its associated big price tag, powerful engine and subsequent high running costs. It's an RS lite, if you will, keep reading to find out exactly what S line gets you. 

Audi S line exterior

Audi S line is designed to bridge the gap between common-or-garden Audi models – the Technik and Sport trims of this world – and the truly sporty versions like the spicy jalfrezi S and the searingly hot RS vindaloo. In other words, S Line is the chicken korma of the Audi lineup – it looks hot and spicy but really, it isn't.

Let's bring this back to the car world with a closer look at the Audi A6. Its range starts with the SE model – it's a smart looking car but not a vehicle you would describe as visually arresting. Step to S line and all that changes. Out goes the apologetic grille and in comes one with gapping air vents that's a feast for your eyes.

Next for the bin are the Sport's plain LED headlights. S line swaps these for Matrix LEDs that not only light up the road better, but also look cooler. Their intricate design is more aesthetically intriguing and your friends will be amazed by the trick welcome dance they perform every time you lock and unlock the car. It's a premium feature that sets your Audi out from the mainstream. 

The most obvious hint that you've bought an S line comes with the 'S line' badge on the wings beneath the A pillars, but actually quite a lot has changed in profile versus a Sport model. The chunkier front bumper flows into more angular side skirts and the arches are now occupied by 19-inch wheels in place of the 18s you get in Sport models. 

Their size is amplified by standard sports suspension which is 20mm lower and firmer than standard and the tinted privacy glass fitted to the back windows adds to the menace.

The whole look is finished off at the back, with what Audi optimistically terms a rear 'diffuser' with mat black plastics and chrome surrounds for the tail pipes. 

Audi S line interior

The changes don't stop with the exterior. Inside an Audi A6 S line you'll be greeted by illuminated kickplates before you snuggle into sports seats that offer more lateral support than the standard car's. As well as getting lumbar support and heating (standard on all A6s) they add electrical adjustment and the driver's seat has a memory function so it's quick and easy to return it to your position. 

On top of that, you get a sports steering wheel with contrast stitching, stainless steel pedals, black headlining and Matt brushed aluminium trim pieces. Again, all this makes an S line car feel like a sporty S or RS model, even from inside.

Why would you buy an Audi S line?

The beauty of choosing an S line model is that you get the sporty looks, but without the expense of buying a genuinely sporty S or RS. Taking the A6 as an example again, it has a basic price of £40,375, spec-up to S line and the price creeps up to £44,035 but that's still a huge saving off the quick S6 (£60,575) and outrageously fast and very pricy RS6 Avant (£92,550).

And that's before you take a gander at running costs. You see, the S line can be had with all the A6's standard engines – petrols and diesels ranging from 204-340PS – that'll return fuel economy of up to 52mpg (40 TDI diesel) – more than double what you can expect from the petrol RS6 and 25% better than even the S6 diesel will manage.

Why wouldn't you buy an Audi S line?

You've heard the expression 'all shirt and no trousers', right? Well, that's the sort of accusation you'll find aimed at you when you own an Audi S line – it looks quick, but really it's no quicker than a regular model with the same engine. 

That 40 TDI diesel we talked about earlier – the one that gets fuel economy of more than 50mpg – well, its thriftiness does come at the cost of performance. It gets from 0-62mph in 8.1 seconds – three seconds slower than the S6 diesel and double the time it takes the 600PS RS6 to explode to 62.

Meanwhile, while S line models get lowered suspension, they don't necessarily have the quattro four-wheel drive you get on S and RS cars and they definitely don't have the clever differentials and huge brakes that make these sporty versions so capable on a twisting country road.