The roar of jet engines swelled to a crescendo as the world's one and only Jaguar C-X75 mid-engined supercar began to accelerate away from a standstill, down the taxiway. It was, I realized, an experience I'd been missing all my life. At various isolated times over the past 60 years of motoring history, far-sighted companies have built road and racecars powered by gas turbines – jets to you and me – but they've not been cars ordinary road testers could expect to get behind the wheel of. Yet the smoothness, the power, all that noise of a heated, hugely swollen volume of gas…it was amazing.
Unfortunately, it wasn't coming from the two little jet engines, no bigger than a couple of thermos flasks, lying flat behind my head under the clear engine bay above the C-X75's rear wheels. We were at San Diego's airport, ahead of the Los Angeles Auto Show where Jaguar's amazing C-X75 show car was set to make its U.S. debut. We were driving Jaguar's 75th anniversary jet supercar on taxiways where license plates and road equipment weren't necessary. But the sound effects this sunny Sunday morning were being supplied by a stream of departing business jets owned by Hollywood-based luminaries such as John Travolta and Tom Cruise; it was amazing how many locals seemed to have urgent business for their Lears and Citations this morning.
Apart from its wonderful shape – which brilliantly combines 2015 modernity with surfaces and proportions that could only be from Jaguar – the C-X75's twin showpieces are tiny turbines, made in England by Bladon Jets. Unlike jet cars of the past, they don't drive the wheels. Instead, they run tiny, fist-sized generators to make electrical power for what is actually a four-motor, four-wheel-drive electric car.
This, in a nutshell, was why the engines weren't likely to be started on our San Diego test drive. They simply didn't need to be run to demonstrate the C-X75's awesome performance. The car's 19.6kWh embedded lithium ion battery bank could be sufficiently charged to cater to our needs on this exclusive drive of the $1.5 million prototype, even before the curious crowds in L.A. could clap eyes on it. Other good reasons were that Jaguar didn't want to scorch its elegantly shaped, ceramic-tipped diffuser with exhaust gas, which exits the tiny jet pipes at 716 degrees (provided the car is doing 30mph or more), and the San Diego airport authorities reckoned they were stretching enough of a point, without allowing such impromptu experimentation. Proper testing of the jets, which run on diesel, will have to await the car's repatriation to the UK.
According to Nigel Taylor, the project's lead engineer, the C-X75 was spun off Jaguar's Limo-Green electric sedan project, as a kind of skunk works job. The company's engineers had started talking about a super-Jaguar with an ultra-modern drivetrain with design bosses Ian Callum and Julian Thomson – something that would truly demonstrate how efficient supercars could be in the future. Aided by technical lessons from Limo-Green, Taylor and company developed a collection of mathematical models that could deliver Bugatti Veyron-level performance figures, while the designers came up with supercar concepts (and JLR's parent, Tata, provided a helpful prompt by becoming an investor in Bladon Jets). The result was the C-X75, a car with a remarkably low weight of 2,976lbs and consequent spectacular performance: 0-62mph in 3.4sec, 0-100mph in 5.5sec, 0-300kph (186mph) in 15.7sec and a top speed of 330kph (205mph).
All this could be achieved, engineers reckoned, for the paltry test cycle CO2 output of 28g/km, or around 150g/km with the turbines running. In real life, they can run independently; just one is needed for constant 100mph cruising. With the pair, a 140mph cruise is possible.
The car has an electric-only range just short of 70 miles. With this and the 16-gallon diesel fuel tank, it has a 560-mile range – an average of nearly 40mpg. These are extraordinary, rule-changing figures for a car with 778hp and 1180lb-ft of torque on tap, and a big part of whose secret is a pair of 94hp gas turbines that weigh just 77lbs each with generators attached, feeding a 507lb lithium ion battery bank. A conventional gasoline engine with generator – much larger, with many more moving parts – would weigh much more.
For all its exotic nature, the C-X75 is relatively simple in concept. It is smaller and lower than most supercars of its awesome potential, yet it has generous conventionally hinged doors, sensibly sized windows, reasonable rear vision and a roomy cabin. The advantage comes, Thomson says, because the mechanical components are all compact, the heavy ones can be mounted low down, and the others can be “scattered about.” The custom chassis is a folded aluminum sheet construction with ultra-stiff independent suspension (the designers' priority with a show car is to have iron control of stance and ride height) but the suspension is all independent, there are huge ventilated discs and the wheels are the biggest yet on a Jag: 22-inch chromed, spoked alloys wearing 365/25 ZR22 Pirellis on the rear, with 265/30 ZR21s at the front.
There are four electric traction motors, each with the equivalent of 195hp on tap, mounted as front and rear pairs in diff-like positions, but each driving its own halfshaft and wheel. The system potentially offers a new level of steering assist, traction control, brake assist and chassis stability functions, since each motor can respond to requests for torque variations even faster than a latest-generation conventional ABS system. As Taylor puts it, it's all a matter of what you can dream up.
The C-X75 perfectly demonstrates the concept that tomorrow's cars won't have mere skins, but a collection of fairings and surfaces and ducts which manage air that flows both over, under and through the car. A variety of inlets collect air to cool the battery in some modes of use, or to close it off at others. There are moving aero devices front and rear for stability (including rear “cheeks” on the body that move out at speed to keep the airstream attached). There is a system that collects cold air for cabin ventilation and to feed the turbines – roughly double the amount a 5.0-liter V8 would need – and another that mixes cold air with hot exhaust gas to cool it (and avoid blistering the hood of the Toyota Corolla behind). Underbody air is controlled by careful shaping, and by a suspension that automatically lowers at speed. Maybe it sounds complex, but the whole system is controlled by microprocessors that take the “housekeeping” decisions out of the driver's hands.
Driving is simple, yet as you slip behind the wheel and into the hard seats (understandably shaped for show appearance, not long-distance comfort), it's hard not to lose yourself in admiration for the profusion of entirely fresh ideas in this car. There's a beautiful one-piece “sculpture” of panel-beaten aluminum lining the whole door aperture.
Callum says Jaguar's major suppliers were encouraged to “get crazy” with concepts, so the doors and bulkhead are covered with upward of 250 tiny Bowers & Wilkins directional speakers, the size of those in mobile phones, for a completely new quality of sound. The twin-dial instrument layout is actually a TFT screen, with gimbal-style readouts for speed and power consumption (the dream ticket is to be charge neutral and the right-hand dial shows you how to do it), while LED bars around the outside show you the activity of each turbine. They take about 15 seconds to spool up and, according to Taylor, are very quiet when you're in the car.
There's another screen by the dials for iPhone-style pages for other functions, plus a circular display on the console to show the functions of the elegant fore-aft “gear” selector. Actually, the 8000rpm electric motors are simply geared to the wheels at a 3.1:1 reduction ratio, and need no clutch, but there are Normal, EV and Track modes which alter the instrumentation. In Track, for instance, you can pull up a timing screen, set the suspension for a stiffer, lowered setup, and even pull up a map of the circuit you might be driving on – complete with real-time advice about cornering lines and braking points. It would take quite a pessimist to say this electric car was less than inviting and exciting.
The C-X75 drives at present like a concept car, with heavy steering, a restricted lock and less performance than its exotic specification implies. Neither is it ever likely to be made for production, though designers and engineers insist that – like Limo-Green – it has taught them a tremendous amount, and its shapes and ideas will survive. Despite the C-X75's one-off nature, there are important and enticing facets for the supercar driver, including good visibility, an airy cabin and a driving position exactly between the front and rear wheel pairs which – for once – is entirely uncompromised by the mechanical layout.
This car, designed entirely in Whitley and made entirely in Gaydon, speaks volumes for the capabilities of those who made it, and for the fine new Jaguars they are preparing for us to buy.