Caterham Roadsport 150 Sigma

It’s hard to imagine two more different cars than a Caterham Seven and an Audi RS6. Both claim to be high-performance machines, but that’s where the similarities end.

Parked next to the Audi, the Caterham looks like a toy. With its chrome lights and mudguards, the basic design is little changed from the original Lotus Seven of 1957.

The RS6 takes the standard A6 Avant and adds flared wheelarches, a bolder grille and a rear diffuser. As with most performance Audis, the changes are subtle, although there’s enough aggression to make it clear this is not a normal estate car.

And the interior exudes the same sporty exclusivity. The already impeccably crafted A6 cabin is enhanced with a smattering of carbon fibre, aluminium and Alcantara. The lovely flat-bottomed steering wheel is great to hold and the well bolstered sports seats are very supportive during hard cornering.

As a result, the cabin of the RS6 is always comfortable and cosseting, whether you’re cruising on the motorway or attacking the corners of a race circuit at high speeds.

Unsurprisingly, the Caterham is the exact opposite. To get in you have to stand on the seat, take your weight on to your arms and then slide your legs down into the narrow footwell. But once aboard, it’s surprisingly cosy. The leather seat slides back and forth and the simple dials and toggle switches are a lovely hint to times past. Yet it can get hot in here, with the exhaust running down the side of the chassis next to the driver. The windscreen and pop-up roof are nods to practicality, but make no mistake: a Caterham is still extreme to drive. Engine heat and noise make long journeys an adventure, although it’s this sense of being at one with the mechanicals that lies at the heart of the Seven’s appeal.

Despite the Fifties-inspired technology, under the thin aluminium bonnet lies a modern 1.6-litre Ford Focus unit. Fitted with a unique throttle body and engine management system, the 150bhp four-cylinder is tiny next to the Audi’s V10.

But as the Caterham is 1,475kg lighter, its power-to-weight ratio is only 14bhp per tonne behind the RS6’s – and as a result, it was a mere nine-tenths-of-a-second slower from 0-60mph, at 5.5 seconds. Launching the Caterham from a standstill requires skill, but balancing the throttle and clutch to limit wheelspin is part of the fun. In the Audi, you push the throttle to the carpet and the quattro 4WD’s strong traction ensures effortless, fuss-free progress.

But that’s not to say there’s no pleasure to be had in the Avant. The V10’s subdued growl and the lovely warbling noise of each gearchange mean it has character to match its scintillating pace. And even though the car weighs more than two tonnes, the huge brakes brought it to a halt from 70mph in 46.9 metres – that’s 3.5 metres less than the non-ABS-equipped Caterham.

It doesn’t really matter how much power you add or how big the brakes are, however; you simply can’t escape the Audi’s sheer bulk. Even though the Dynamic Ride Control active dampers restrict body roll superbly, the RS6 never feels as agile as the feather-light Caterham.

The Audi is still impressive on the track. It turns in positively, has masses of grip and is incredibly composed at high speed. With the four-wheel drive split 40-60 towards the rear, it resists pushing its nose wide, too.

But it’s worth remembering that if you use the RS6 hard on a track, its costly tyres and brakes would wear out quickly. The Seven is easier on its cheaper consumables, and yet remains wonderfully engaging.

While the latest Roadsport chassis is 14 per cent stiffer than before, the basic Caterham mix of unassisted steering and brakes, relatively soft suspension and kart-like responses is unaltered. Turning into a corner, the car can be directed using a combination of the throttle and steering. There’s always plenty of warning when the limit of grip arrives, while the gearbox has a pleasing short throw and you can entertain yourself by getting the changes super-smooth. In short, few cars offer the pure driving fun of this legendary British roadster, and it’s perfect company for experienced drivers or beginners.

You enjoy the RS6 for its massive speed and technical ability, while you revel in the Caterham for the pure act of driving. One is akin to flying business class in a private jet; the other is similar to taking a ride in a classic Tiger Moth biplane. Both are great experiences. But which is better?

Details

WHY: With its pace and handling, the RS6 is a real track day thriller. Is it a better buy than the ultra-focused Caterham Roadsport 150 Sigma?

Economy

A unique car to own, and running costs depend on how much you use it. Caterham doesn’t have a main dealer network, and independents do most servicing. But as the Roadsport’s mechanicals are so simple, many drivers maintain their own car. Insurance is the cheapest here, too, and although our experts don’t quote official residual figures for the car, the enthusiastic fan base means well cared for examples fetch excellent money second-hand.