The gap between the residual values of prestige-brand vehicles fitted with an automatic gearbox and those without has widened markedly over the past two years, according to a publisher of used car price guides.

EurotaxGlass's said the popularity of automatic transmissions is such that the original purchase price is often now more than recouped when a prestige vehicle is resold.

The premium for an automatic gearbox typically increases with the size of the car. For example, on a six-month-old Mercedes A-Class the residual value premium for a car with an automatic gearbox compared to one without is around £750. For a C-Class of the same age the premium increases to £1,650. On a CLK or E-Class the margin widens to £1,925, and for an M-Class SUV it is a significant £2,500 - well above the original £1,450 cost of the automatic option.

The premium also increases the further up the engine range buyers go. A BMW 318i SE with an automatic transmission is worth an additional £1,000 after six months, but, for larger engine versions, the premium increases in clear steps - £1,450 for the 320 SE, £1,625 for the 325 SE and £1,925 for the 330 SE.

"Recent advances in technology have yielded improvements in the driving dynamics and fuel economy of automatic gearboxes, boosting demand across both the new and used prestige car markets," said Richard Crosthwaite, prestige car editor for EurotaxGlass's.

"There is little doubt that the increases in residual values appear to be sustainable in the coming months, although we doubt that the recent upward trend will continue at its current rate."

Although the highlighted data relates to six-month-old cars, sometimes referred to as 'nearly news' by the UK motor trade, the publisher reported a similar pattern with older vehicles.