The Radical SR3 is the most road-biased car yet from this track-car company

We hate to say it, but we've been here before with cars similar to the Radical SR3 SL. Had we been dropped a few quid every time a fledgling car manufacturer promised (and subsequently failed) to rejuvenate the sports car market, Autocar would be brought to you from the Bahamas.

But among the empty factories and unpaid bills sometimes arrives a gem of a company – one that establishes itself with a sound business plan and survives thanks to sound products. A gem of a company, such as Radical.

Radical's range also includes more high-performance models, like the V8-powered SR8 RX

Radical was founded in 1997 to take advantage of the increased enthusiasm for track days. Its first cars –  motorbike-engined ones that could be made road legal – were so well received that Radical decided to create a one-make race series.

Since its inception more than 1000 cars, of various types but all similar in ethos, have rolled through the factory’s doors. One even rolled convincingly around the 24 Hours of Le Mans in 2009, finishing 20th overall.

Many have been road legal, but none has been as actively road biased as the SR3 SL you see here.



15in Radical SR3 SL alloys

At first glance the SR3 SL still looks like a pitlane refugee, but closer inspection reveals there are areas where it departs from the Radical norm. The existing SR3 is Radical’s most popular car – more than 600 have been sold – and while they can be made road legal, many are not and that is not their ethos.

The SR3 SL, though, is different. The ‘SL’ in the name stands for Street Legal; instead of the IVA single-vehicle type approval process that has previously been applied to the SR3 (limiting the number of cars that can be road registered to 300), the SL has been through the European type approval process.

The Ford engine features variable cam timing, a fly-by-wire throttle and bespoke engine management

This allows Radical to make up to 2000 cars and sell them throughout the EU – and mainland Europe is where much of the demand has come from. It’s not a simple process, and it isn’t cheap (Radical has invested in the region of £750,000 doing it). 

Visually, there are some obvious changes, such as broader radii around the front splitter and the cockpit edge. The rear wing is narrower so that it doesn’t reach the body’s edges, and the wheels sit further inboard than usual. They all lend the SL a slightly odd look that’s less pure than other Radicals. It looks less fast.

However, the significant changes are beneath the car’s glassfibre bodywork. Radicals traditionally come equipped with a superbike engine of 1300-1500cc (usually a Suzuki Hayabusa-derived unit), but the SL has a Ford 2.0-litre turbocharged motor, developing 300bhp.

Why the Ford unit? It meets Euro 5 emissions regulations and is new, so it should lead a prolonged life (it will eventually get through Euro 6, too). It also requires no overtly complicated modifications to output 300bhp either, so it’s cheaper than, say, the Cosworth-tuned 2.3-litre unit used by Caterham and BAC. A potential downside is some whooshy turbo lag, which can be no great fun in a car this light; the SL tipped our scales at 765kg.

The engine is bolted to a six-speed sequential transaxle, which encompasses a limited-slip differential and is supplied by Quaife to a unique Radical specification, while shifts are by Radical’s own pneumatic actuator.

The whole shebang is fitted to an FIA-approved steel spaceframe, with aluminium front crash structure and double wishbones at either end.


Radical SR3 SL dashboard

It was no secret that Radical wanted to build a coupé, and that played a major part in the decision to put the SR3 SL through European type approval; it got in before the November 2011 deadline, after which cars obtaining type approval will have to be fitted with the electronic driving aids that the SL does without.

Some things, though, it can’t ignore. The SL’s interior is bedecked with more fripperies than we’ve come to expect in cars like this. Not loads of them, but the seats are a sliding moulded bench, with integral headrests rather than pads on the roll bars as in other Radicals.

The Radical even features heated and electrically adjustable mirrors

The steering wheel is padded, too, and even the horn buttons are required by legislation to face right from the wheel. And you can adjust the electric mirrors from the driver’s seat.

There is even a light and – again, a legislative requirement – a heater. It doesn’t have to work very well, mind you (and the SL’s doesn’t), but it does have to be there. These, however, all count as valuable elements for the road-legal and slightly more usable Radical RXC coupé.

Beyond the legislative nonsense, though, you’ll find that the SL’s is a cockpit built for driving as much as any other Radical's. The driving position is good (though two occupants will want for shoulder room), with the harnesses securing you in your seat where the modest bolstering will not.

The view out is terrific, too, and those diddy front wings help to place the car with ease. Given a few minutes to build familiarity, you’ll find the switchgear and instruments are as straightforward as any rival’s.

Don’t expect much practicality, though. A Caterham offers a boot; even an Ariel Atom has a small cubby. The SR3 SL’s shape dictates that it doesn’t. There is a 12v power socket, though.


Radical SR3 SL side profile

If you’re looking for variety here, you’re in the wrong place. The Radical SR3 can be had with the aforementioned 245bhp Ford Ecoboost engine and six-speed sequential transmission. And that’s it. 

As you’d hope for an engine whose internals are unchanged since Ford fitted them, the SR3 SL’s motor starts easily on the button and settles to a notably restrained idle.

Retardation and pedal feel are good in the dry. In the wet it’s a different story

For those used to other Radicals, the lack of chatter and zing will come as a surprise, but it is by no means an unpleasant one. Especially if you’re going to use the SL on the road, as you ought to. Engaging a gear still emits a clonk, but the clutch is easy.

Throttle response for a turbocharged engine is good; inevitably it’s less sharp than a normally aspirated engine, but if you had 2.0 litres and 300bhp without forced induction you’d be paying a bigger price at low revs. 

If you’re asking a lot of the engine then you can forget about using the clutch and revel in upshifts that are pulled through seemingly as quickly as any twin-clutch transmission. Clutchless downshifts are on the cards if you’re completely off the throttle too.

In ideal conditions Radical claims that the SR3 SL can hit 60mph from rest in 3.4sec and 100mph in 8.4sec. Top speed, if you've the room, is a substantial 161mph.

Despite the conditions, traction is good, and although there are no driving aids per se, turbo boost and torque are limited in first and second gear. There’s no ABS, either, but retardation and pedal feel are good in the dry. In the wet it’s a different story; retardation is okay, but it’s hard to tell when a wheel is locking.


Radical SR3 SL cornering

If you’re looking for a road car in which you can occasionally pop along to a race track, shop elsewhere. Radical has modified the SR3's chassis to make the SL friendlier for the road – it runs less negative camber than regular SR3s, for example – but there’s only so much you can do to a pseudo-racing car.

The SL remains a tiring roadgoing companion, chasing after cambers and tramlining like a cat pawing at a ball of wool. It doesn’t glide across surfaces impervious to imperfections in the way a Lotus 2-Eleven does; nor is it as composed as an Ariel Atom or Caterham Seven.

The SL remains a tiring roadgoing companion

There’s still amusement to be had, however. Overtakes are easy thanks to the deep swell of torque and fine visibility, while the sheer view out, across those front wings, is far too reminiscent of a prototype sports car to be anything other than a hilarious and fascinating blast.

But those sports prototype looks tell you where the SL really belongs, which is in the same place as all other Radicals: on smooth, one-way roads with no speed limits and a marshal at each corner. On a circuit, the SL is superb.

Its bigger-capacity turbocharged engine makes it a less frenzied experience than most other Radicals or, say, Ariel’s Atom V8. But unless you’ve slapped numbers on the side and are running against pure racing variants of the SR3, there’s all the pace and focus you could hope for.

Any grip deficiencies offered by the road-friendly Kumho tyres is more than offset by the aerodyanmic grip, while the overall balance of the SL’s chassis is sound, with a forgiving limit that it urges you to find.

And while it would be easier to play with its line without the boost and lag, traction and grip are so good that it really isn’t a major issue. That the Radical SR3 SL is easy on its consumables, as befits a 765kg car, means that pounding around your favourite circuit, lap after lap, is an addictive experience.


Radical SR3 SL

If you’re after a car like the Radical SR3, it’s fair to say you’ll know what you’re getting into. The purchase price is high and, while running costs don’t necessarily have to be, it’s usually better for the soul to work them out by the year rather than by the mile.

And it’s perhaps better not to work out the ancillary costs at all – track charges, the price of a trailer, licensing, that sort of thing.

The Radical should prove reliable, and go through its consumables at a manageable rate

However, lightweight cars like the SR3 SL shrug off repeated track use without a continual demand for new brakes and tyres, while they generally hold their value strongly, too. Many pre-owned Radicals get sold through the factory, and benefit from a high retained value.

If you’re worried about economy you’re probably looking at the wrong sort of car, but in something this light and with a fairly unstressed engine you’re looking at a lighter financial burden at the fuel pumps than many rivals.

We even managed 14.2mpg average during our track test. Not bad for an extended and very unforgiving session on circuit. 


4 star Radical SR3 SL

Delivering a verdict on a car with such a singularity of mind as the Radical SR3 SL isn’t easy. Would it not be more affordable to buy an old racing car and a trailer? Yes, it would.

However, that is to miss the point of this car; there are those who want a track-focused car that can, however irregularly, be used on the road.

The SR3 SL is one of the most enjoyable track cars we’ve driven, and it represents a very enticing proposition for those seeking a track-focussed toy

They want it new and exciting, and that is the purpose for which we must judge the SR3 SL’s fitness.

It’s not without faults, but those it does have are typically of a minor nature.

It could be a better-mannered road car, it could have sharper throttle response and its brakes ought to be more easily modulated in the wet. But those are small quibbles.

Overall, the Radical SR3 SL is one of the most intoxicating and appealing track cars we’ve ever driven.

For us, its shortcomings as a road car wouldn’t break the deal.

Matt Prior

Matt Prior
Title: Editor-at-large

Matt is Autocar’s lead features writer and presenter, is the main face of Autocar’s YouTube channel, presents the My Week In Cars podcast and has written his weekly column, Tester’s Notes, since 2013.

Matt is an automotive engineer who has been writing and talking about cars since 1997. He joined Autocar in 2005 as deputy road test editor, prior to which he was road test editor and world rally editor for Channel 4’s automotive website, 4Car. 

Into all things engineering and automotive from any era, Matt is as comfortable regularly contributing to sibling titles Move Electric and Classic & Sports Car as he is writing for Autocar. He has a racing licence, and some malfunctioning classic cars and motorbikes. 

Radical SR3 First drives