Knowledge of fuel mass injected in an individual cycle is important for engine performance and modeling. At the moment, such measurements are not possible on-engine or in real-time. In this paper, a new method using Coriolis flow meters (CFMs) and a new, patented, signal processing technique, known as the Prism, is introduced. CFMs are extensively used for flow measurement both in the automotive industry and further afield, and when coupled with the Prism have the potential to make these challenging high-speed measurements. A rig-based feasibility study was conducted injecting very small quantities of diesel (3 mg) at pressures of up to 1000 bar at simulated engine speeds of up to 4000 rpm. The results show that these small quantities can in principle be measured. The results also reveal a previously unknown behaviour of CFMs when measuring very low flow rates at high speed. The study concludes that by combining high-resonant frequency flow tubes with the Prism technology in a new instrument—the Fast Next Generation Coriolis (Fast-NGC) flow meter—it will be possible to measure individual injector flow rates on-engine in real-time.