The residual values of used convertibles increased, month-on-month, by up to 5% during May, as demand improved in response to prolonged spells of dry and sunny weather.

Reporting on the seasonal uplift in values, EurotaxGlass’s has found that a number of volume-brand drop-tops retain a far greater proportion of their value than prestige-brand models from the likes of BMW, Lexus and Maserati.

While the Ferrari F430 Spider holds onto its value better than any other 12-month-old convertible on sale in the UK (a typical ’06-plate example retaining 97% of its original list price as a trade value), hot on its heels is the rather more humble Volkswagen Eos (at 94% retained value in 2.0 TDI Sport guise).

“This analysis offers some stark examples of how changing patterns of supply and demand are challenging the market’s preconceptions of which cars hold their value best,” said Jeff Paterson, senior car editor at EurotaxGlass’s.

“Few would expect convertibles such as the Vauxhall Astra Twin Top and Mitsubishi Colt Cabriolet to boast residual values stronger than those of a BMW Z4.”

Below the Volkswagen Eos, in joint third spot, are the Porsche Boxster S and Mercedes-Benz SLK55 AMG (87%). Close behind in fifth place is the Mini Cooper S convertible (85%), whose mighty residual value performance is identical to that of two high-performance prestige models, the Audi RS4 Cabriolet, and the Jaguar XK Convertible.

Rounding off the ‘top 10’ are the Porsche 911 3.8 Carrera S Convertible (84%), the Aston Martin DB9 Volante Convertible (82%), and the Mazda MX-5 1.8 Convertible and BMW 330d Convertible (both at 78%).

EurotaxGlass’s says the convertible market continues to be affected by seasonal peaks and troughs - values fall at a more pronounced rate than the rest of the used car market in autumn and winter, then rise in spring when conventional cars continue to fall in value.

What has been noticeable this spring is that the recovery in prices has not been as marked, largely due to additional supply created from rising new car sales in previous years.

“It is clear that coupe-convertible cars with a folding metal roof are affected less by these seasonal patterns than fabric-roof models,” adds Paterson.

There are signs that some buyers are not embracing the coupe-convertible (folding hard-top) format for aesthetic reasons.

Dealers representing a variety of marques have reported that some prospective buyers have rejected coupe-convertibles on the basis that it is less obvious to the outside world that they are driving a convertible when the roof is up.

“It seems discreet coupe-convertible styling does not flatter the vanity of some owners,” says Paterson.

#AM_ART_SPLIT# Furthermore, while practicality is not high up on the agenda of used car buyers, a folding metal roof does compromise boot space more severely than a fabric roof.

Richard Crosthwaite, prestige car editor at EurotaxGlass’s, said: “This is a fashion-led market, where the values of prestige-brand models in particular are influenced by changing tastes and the arrival of new models.

“Ownership periods are typically shorter than for conventional road cars, with buyers more likely to swap into what they perceive to be the ‘next big thing’. This can make the residual value of a recently-launched prestige convertible amongst the strongest of any used car when supplies are limited. However, even when they are past their first flush of youth, these cars often still boast values that outperform much of the rest of the market - even outside the peak spring/summer season for convertible sales.”

Top 20 used convertibles - ranked by retained trade value after 12 months (2006 ’06-plate)

Model and (retained value)

1 Ferrari F430 Spider (97%)
2 Volkswagen Eos 2.0 TDI Sport (94%)
3= Porsche Boxster S (87%)
3= Mercedes-Benz SLK55 (87%)
5= MINI 1.6 Cooper S (Chilli) Convertible (85%)
5= Audi RS4 Cabriolet (85%)
5= Jaguar XK Convertible (85%)
8 Porsche 911 3.8 Carrera S Cabriolet (84%)
9 Aston Martin DB9 Volante Convertible (82%)
10 Mazda MX-5 1.8i (78%)
11 BMW 330Cd Sport Convertible (78%)
12= Mercedes-Benz SL350 Convertible (77%)
12= Honda S2000 2.0i VTEC (77%)
14 Mercedes-Benz CLK200 Kompressor Avantgarde Cabriolet (76%)
15= Vauxhall Astra 1.9 CDTi 16v (150ps) Twin Top Sport Coupe (75%)
15= Mitsubishi Colt 1.5 CZC Turbo Cabriolet (75%)
15= Lotus Elise 1.8 R (75%)
15= Peugeot 206 1.6 HDi 110 Allure Coupe-Cabriolet (75%) 15= BMW Z4 2.5i Sport (75%) 20 Audi TT Roadster 1.8 T (150 bhp) (74%)