In 1971, the Jaguar E-Type Series III introduced the V12 engine to the model. This raised the car’s appeal on paper by having much more exotic specification. Jaguar called it the “Ultimate Cat” and advertised the car’s inherent smoothness and absence of engine noise.
Both the Coupe and Roadster were built on the longer 2+2 chassis which meant the Borg Warner automatic transmission was available on all V12 xkes.
Weighing in at 680 lbs (300 kgs) the small block V12 displaced 5.3 liters and produced 314 horsepower. It was an all-new sohc V12 utilizing four Stromberg carburetors.
Much of the E-Type structure had to change to accommodate the new V12 including widening of the engine subframes and a wider track. This included using the Saloon rear subframe assembly which added 3.25 inches of track.
Visually the car had a new eggcrate grill, wheel arch flares, four exhaust tips. Mechanical upgrades included larger brake discs and a larger fuel tank.
Inside the V12 had an entirely new interior with new reclining seats, a plastic center console, new door panels and a revised steering wheel. The dashboard retained much of the Series II layout, but included the 2+2 stowage areas above the floorwells.
Production of the Series III roadster reached 7,992 cars.
| type | Series Production Car |
| built at | Coventry, England |
| production | 7992 |
| price $ | $ 7,599 |
| engine | 60º V12 |
| position | Front Longitudinal |
| aspiration | Natural |
| valvetrain | SOHC |
| fuel feed | 4 Zenith Stromberg 175 CD2SE |
| displacement | 5343 cc / 326.0 in³ |
| bore | 90 mm / 3.543 in |
| stroke | 70 mm / 2.756 in |
| compression | 9.0:1 |
| power | 234.1 kw / 314 bhp @ 6200 rpm |
| specific output | 58.77 bhp per litre |
| bhp/weight | 204.83 bhp per tonne |
| torque | 473.2 nm / 349 ft lbs @ 3800 rpm |
| body / frame | Unitary Steel Monocoque w/Front Subframe |
| driven wheels | RWD |
| wheel type | Steel Discs or Spoked Wires |
| front tires | Dunlop E70VR-15 SP |
| rear tires | Dunlop E70VR-15 SP |
| front brakes | Ventilated Discs w/Vacuum Asssist |
| rear brakes | Solid Discs w/Vacuum Asssist |
| front wheels | F 38.1 x 15.2 cm / 15.0 x 6.0 in |
| rear wheels | R 38.1 x 15.2 cm / 15.0 x 6.0 in |
| steering | Rack & Pinion w/Power Assist |
| f suspension | Wishbones w/Torsion Bars, Hydrualic Telescopic Dampers |
| r suspension | Half Shafts w/Transverse Links, Twin Coil Springs, Hydrualic Telescopic Dampers |
| curb weight | 1533 kg / 3380 lbs |
| wheelbase | 2659 mm / 104.7 in |
| front track | 1382 mm / 54.4 in |
| rear track | 1356 mm / 53.4 in |
| length | 4684 mm / 184.4 in |
| width | 1679 mm / 66.1 in |
| height | 1222 mm / 48.1 in |
| transmission | 4-Speed Manual or Optional 3-Speed Auto |
| tran clutch | Bord & Beck |
| gear ratios | 2.93:1, 1.90:1, 1.39:1, 1.00:1 |
| final drive | 3.54:1 |
| top speed | ~217.3 kph / 135.0 mph |
| 0 – 60 mph | ~6.8 seconds |
| 0 – 100 mph | ~18.5 seconds |
| 0 – 1/4 mile | ~14.8 seconds |
| fuel capacity | 76.65 litres |
