The Dassault Mercure was a short-range twin-jet airliner. It was canceled with sales not reaching the breakeven point. Other similar jetliners like the Boeing 737 had a more convenient longer range.
The structural design features of the Mercure precluded increasing the fuel capacity, but there are jet fighters where conformal fuel tanks were added, same as in the Hypersonic experimental X-15.
Are this type of added fuel tanks a feasible option for increasing the Mercure range?