It says the value of used prestige-badge luxury cars, such as the BMW 7-series, Mercedes S-class and Audi A8, now fall short of the market average if the vehicle is not fitted with sat-nav.
The company suggests that used buyers will either dismiss a luxury vehicle without such technology or will expect up to £2,500 to be taken off the asking price.
'Satellite navigation should no longer be viewed as an indulgence for prospective buyers of new luxury cars,' said Richard Crosthwaite, prestige car editor at Glass's Information Services.
'It has become a crucial investment, underpinning the future residual value of the vehicle. Our analysis of the market demonstrates that the initial outlay will be more than recovered when it comes to sell the car to its next owner.'
Crosthwaite added: 'This kind of technology is now a standard feature throughout the Mercedes S-class range, but it remains an option on many other vehicles in the class and buyers should not hesitate to tick the 'sat-nav' box on the options list.'
The company predicts that within two years, satellite navigation systems will become similarly crucial for owners looking to achieve the typical market value for a smaller used prestige badge vehicle, such as a BMW 5-series or Mercedes E-class.
Crosthwaite said: 'As sat-nav systems become prevalent, used car buyers will expect to see such systems appear on more premium-badged cars.
'This is already happening with larger-capacity engine models in this sector and with prestige sports utility vehicles, where securing the optimum market value is steadily becoming more dependent upon the inclusion of sat-nav.'
|Impact of sat-nav RVs on luxury cars (2 years, 24,000 miles)|
|Model||RV with sat-nav||RV without sat-nav||Variation|
|Mercedes-Benz S320 auto:||£29,825||£27,325||£2,500|
|BMW 735i Sport auto:||£23,650||£21,300||£2,350|
|Audi A8 3.7 quattro auto:||£22,425||£20,175||£2,250|
|Jaguar XJR 4.0 auto:||£26,975||£24,725||£2,200|