Using the earlier 3½-litre engine as a starting point, Alvis increased its capacity to 4387cc for its range-topping Tourer. Power was uprated to 137bhp giving the 4.3 a top speed of just over 100mph. No chassis modifications were needed to house the new 4.3 unit, which helped to keep the development costs down. Unlike its forerunner, the 4.3 was sold with a standard body, produced by the Coventry-based coachbuilder Charlesworth. The Vanden Plas-bodied 4.3 was the fastest British car at the time, thanks in part to its short, light weight chassis.