  Quintessential inflation describes a scenario in which both inflation and
dark energy (quintessence) are described by the same scalar field. In
conventional braneworld models of quintessential inflation gravitational
particle production is used to reheat the universe. This reheating mechanism is
very inefficient and results in an excessive production of gravity waves which
violate nucleosynthesis constraints and invalidate the model. We describe a new
method of realizing quintessential inflation on the brane in which inflation is
followed by `instant preheating' (Felder, Kofman & Linde 1999). The larger
reheating temperature in this model results in a smaller amplitude of relic
gravity waves which is consistent with nucleosynthesis bounds. The relic
gravity wave background has a `blue' spectrum at high frequencies and is a
generic byproduct of successful quintessential inflation on the brane.
