The oversized airbag steering wheel gets swapped for a smaller three-spoke competition number in Alcantara suede, and the gear lever is replaced for a shorter one. You get special sill protectors, lighter door casings and sliding Perspex windows. Otherwise, well enough is left alone.
Under the bonnet, Bowler fits a new ECU to the car’s Transit-derived 2.2-litre turbodiesel engine, increasing peak power to 170bhp and peak torque to 332lb ft. Downstream of the engine, customers can opt for a mechanical limited slip differential for the rear axle. But that’s it. In all other respects, the Defender powertrain is entirely unaltered, right down to the individual gear ratios.
The car’s rolling chassis has the biggest overhaul. Heavy-duty Bilstein shocks are fitted, as well as stiffer springs and anti-roll bars, and lightweight 18-inch alloys are adopted shod with Kumho rally-raid tyres.
Bowler leaves Land Rover’s standard suspension bushes on the car, but they effectively become a service item to be changed once a season. That gives you an idea of how hard a life these cars will have. On a standard Defender, those bushes last the typical 15-year lifespan of the vehicle.
Almost all the weight the car sheds as a result of the subtractions of fittings from the cabin is put back into it with the roll cage, so a finished Defender Challenge car weighs almost exactly what a standard Defender 90 Hard Top weighs: roughly 1750kg.
The rollcage adds complication to your entry routine, but nothing too terrible. Once you’re through the bars the bucket seats are quite wide-hipped and comfortable, but supportive enough to keep you riveted securely in place during the inevitable rollercoaster ride to come.
The classic upright Defender driving position isn’t the perfect one for the heat of competition. The smaller steering wheel helps to solve the leverage problem Defender drivers have been suffering since time immemorial: it makes more room for your right elbow. The steering column could do with more rake adjustment. Equally, it could do with being in line with the middle of the driver’s seat. The pedals would be easier to operate if they were less upright-of-action, and the footwells were a bit deeper.
But these are problems that Land Rover hasn’t solved in 65 years of continuous product development. It seems a bit much to expect Bowler to cure them overnight.
The car idles noisily once it’s running, even by Defender standards; it rattles the side windows when it revs. You don’t need first gear unless you’re moving off on an incline, and even second feels pretty short given the engine’s operational range. It’ll pull cleanly from low revs, and has a really torquey sweet spot between 2000- and 3000rpm, but it’s suffocating before 4000rpm comes around.
So going fast in this car involves plenty of gear changes. Arm-twirling, too. The Defender’s worm-and-roller-gear steering rack has four turns between locks. The smaller tiller and stiffer springs make the competition car feel about twice as wieldy as a standard Defender just off-centre, but that’s still about half as wieldy as any other rally car you’re ever likely to drive. Committing the nose to a muddy third gear corner requires lots of faith – and a good half turn of lock.
You wouldn’t rush to quicken up that rack though, because once the Defender has turned in, it can be quite a handful on a slippery surface. That famous 88in wheelbase is a bit short for ideal directional stability, as both Bowler and Land Rover will admit. Since it’s much stiffer sprung than a standard Defender, the car can surprise you with a sudden swing of mid-corner oversteer that often requires a full turn of the steering wheel to sort out. Corrections like that certainly focus the mind, and big slip angles aren’t advisable for the car, given the risk of rollover. A precise and disciplined style is absolutely in order – which makes the car perfect for rally-raid driver training, neatly enough.