Jaguar XK8 (X100) 1996-2005 4.2 R 400bhp Stage 1 Eco remap figures
The Stage 1 Eco map for the Jaguar XK8 4.2 R 400bhp (1996-2005): 426bhp and 595Nm expected from a standard 400bhp and 553Nm, up to +26bhp and +42Nm. It keeps most of the Stage 1 gain (Stage 1 is 435bhp and 599Nm) and is tuned with economy in mind: the choice if you want the performance and care what each tank costs.
Choose your map
Stage 1 Eco remap figures
Stage 1 Eco is performance with economy in mind. It keeps most of the Stage 1 gain, so the car still pulls well, but the map is shaped for efficient, relaxed driving rather than flat-out output. It is above the standard figures. We don't quote mpg, because economy depends on the car and how it is driven.
| Stock | Vanguard expected | Expected gain, up to | |
|---|---|---|---|
| Power | 400 bhp | 426 bhp | +26 bhp |
| Torque | 553 Nm | 595 Nm | +42 Nm |
All maps at a glance
| Map | Power | Torque | Expected gain, up to |
|---|---|---|---|
| Stock | 400 bhp | 553 Nm | |
| Stage 1Maximum software-only performance | 435 bhp | 599 Nm | +35 bhp +46 Nm |
| Stage 1 EcoPerformance with economy in mind | 426 bhp | 595 Nm | +26 bhp +42 Nm |
| Eco mapEconomy first | 423 bhp | 593 Nm | +23 bhp +40 Nm |
Who is the Stage 1 Eco map for?
- Naturally aspirated owners who want a little more response and a more efficient, relaxed drive. Every map we list stays above standard.
- Drivers who want the small gain on offer without chasing peak output.
- Anyone who would otherwise take the full Stage 1 map but wants it tuned with economy in mind.
How Stage 1 Eco compares with Stage 1
Full Stage 1 on this Jaguar XK8 is expected to give 435bhp and 599Nm (+35bhp, +46Nm). The Stage 1 Eco keeps about 74% of that power gain and 91% of the torque gain, so you get 426bhp and 595Nm: 9bhp less and 4Nm less than Stage 1, with the map shaped for efficient, relaxed driving, so it suits you if you want the pull and care about running costs. Both sit above the standard 400bhp and 553Nm.
What this means for your XK8
Without a turbocharger the improvement comes from ignition, fuelling and throttle mapping rather than boost, so expect a smaller but still noticeable change in response.
The ECU recorded for this variant is a Denso. Older engine management is simpler to work with, but age matters: worn sensors, leaks and tired components can hold back what a remap delivers, which is why we run a diagnostic check first.
We remap at our Belgrave Gate workshop in Leicester, or at your home or work within 30 miles, and every job starts with a diagnostic check.
Please note: these are expected figures, not guarantees. Real results vary with the condition of the vehicle, the ECU software version, fuel quality and the hardware fitted. Some options - including Stage 2 and anything that needs extra hardware - are for off-road or competition use only. We check every vehicle first and confirm what is achievable before any work starts.
Figures reviewed 22 October 2026.
Stage 1 Eco questions
How much power does the Stage 1 Eco map give the Jaguar XK8 4.2 R 400bhp?
We expect 426bhp and 595Nm against 400bhp and 553Nm as standard: up to +26bhp and +42Nm. These are expected figures, and we confirm what is achievable on your own car after a diagnostic check.
How does Stage 1 Eco differ from Stage 1 on this engine?
Full Stage 1 is expected to give 435bhp and 599Nm. Stage 1 Eco gives 9bhp less and 4Nm less, in exchange for a map shaped with economy in mind. It still sits above the standard figures.
Is Stage 1 Eco or the Eco map better for me?
Choose Stage 1 Eco if you want the performance (426bhp and 595Nm) and still care about running costs. Choose the Eco map (423bhp and 593Nm) if economy matters more than pace.
Will the Stage 1 Eco map save fuel?
It is tuned with economy in mind while keeping most of the Stage 1 performance. We do not quote mpg figures, because economy depends on the car, its condition and how it is driven.
Do I need to tell my insurer about a remap?
Yes. A remap is a modification, so you should declare it to your insurer.
More Jaguar XK8 figures
Other petrol variants
All petrol XK8 (X100) variants · XK8 (X100) 1996-2005 overview · All Jaguar figures