The current Mercury Grand Marquis covers up to 637 km on a full tank, based on combined-cycle consumption. Figures below are the best-range variant in each generation.
| Years | Powertrain | Range |
|---|---|---|
| 1991–1998 | Combustion | 676 |
| 2000–2003 | Combustion | 637 |
Range is calculated from each variant’s fuel tank capacity and combined-cycle consumption (tank ÷ consumption × 100), for the best-range variant in each generation — real-world range varies with driving style and conditions. Figures outside a plausible range for the tank size are excluded.