Hayabusa-based SR3 RS and double-the-fun V8-powered SR8 RX may be, but zero torque below 10,000rpm was never going to work on the road. You can make Radicals road legal if you want to, as Riggers discovered, and Radical has exploited for 'ring recordglory, but that doesn't mean it's necessarily a whole lot of fun.
Demanding a £1.2m investment, type approving the SR3 for European sales brings with it a lot more regulation and red tape than the SL's racecar looks might suggest. So why do it? Demand from export markets apparently, 70 per cent of the cars leaving the Peterborough factory heading overseas. And there's more to come, with a Radical coupe on the way.
Back to the here and now though. From the roll hoop forward it's the same spaceframe chassis as other SR3s, but the longitudinal engine configuration means it uses the same Quaife sequential gearbox as the SR8, pneumatically shifted with racer style paddles. And though the bodywork looks similar the rules demand higher front wings, slats on the side pod intakes to nullify a gruesome sounding 'head entrapment' risk and a taller, narrower rear wing.
The latter doesn't do any favours for the looks, but the rules say it can't be wider than the cockpit. Power adjustment for the Mini-donated mirrors and a higher seating position are also mandated by the rules, the latter for visibility. Which, given the blindspots on a lot of modern cars, seems daft for something with no A-pillars and does lead to a curious sense of being perched on top of the car.
More turbo, fewer revs
Power delivery is punchy in the extreme. It may be connected to a racer's sequential gearbox but this is still a new-school, mainstream, direct-injected and turbocharged engine and gives you the lot from very low revs. This'll be a shock to seasoned Radical drivers, the SL all but done by 6,000rpm. It sounds pretty flat and dull too. Or at least the engine does, the turbocharged whooshes and gurgles coming from the air intake behind your head more than enough to drown out the drone.
You'll also hear many roadtesters prattle on about steering feedback but in the SL it's a case of be careful what you wish for. Stiffer sidewalls on the Dunlop Direzzas on this car and dampers running 10 out of 30 clicks mean it's less chatter from the wheel than full-on shouting, ruts, dips and grooves tugging and pushing. Backing the dampers off to zero would apparently help, ditto the more compliant standard Kumhos.
As previously explored, Radicals do offer superbike pace for four wheels and, though I've never experienced the two-wheeled alternative, the SL's pace is different-league rapid and requires serious recalibration for a car driver's brain. A short straight permits one, two and - just - three flat shifts in succession, the explosion of pent-up boost pressure as I lift for the corner as alarming as the number on the digital speedo. And then a fly splats me between the eyes.
Arriving at Silverstone it's a case of little more than pulling into the garage, grabbing some headgear and driving out. And it's the ease with which you can do this that marks the SL out from other Radicals. No trailer, no faff, no 100-hour engine rebuilds. It's just straight out and into the thick of an already busy trackday.
It's here a degree of frustration sets in - the Radical is so much faster than anything else the straights merely catapult you into another trundle around a corner in the wake of a 'normal' car. Clean laps with no traffic and opportunity to push hard are a rarity, finding the space to develop a rhythm even more unusual.
A case of picking your trackdays carefully then, the performance on the road in the meanwhile ludicrous enough to leave you feeling light-headed and giggly. Words like 'uncompromising' often get bandied about in relation to track-biased cars, but in the Radical's case it really means it, the quality of the engineering beyond question but the functional build perhaps lacking some of the surprise and delight artistry you'd get in a KTM or Atom. Sure, the Radical is fast. But a car that's going to spend at least some of its time on the road sometimes needs more than sheer pace.
If speed is everything the Radical wins. And though it may not look a huge leap from the bike-engined SR3s we know and love, this is actually a huge step for the firm. And as near to accessible as you're going to get.
Track photography by Fresh Orange Phtoography
RADICAL SR3 SL
Engine: 1,999cc 4-cyl, direct injection, turbocharged
Transmission: 6-speed sequential, pneumatically operated
Power (hp): 240@6,000rpm
Torque (lb ft): 265@4,000rpm
Top speed: 161mph
Weight: 775kg (dry)
MPG: 28mpg (NEDC combined)
Price: £69,850 (basic list, race pack including 300hp power upgrade and three-position Manettino an additional £4,000)