Land Rover has been condemned as having the most problem-ridden cars among the world's major motor manufacturers.

It has come bottom of a critical United States car survey which buyers watch closely - a bad blow for sales in a market crucial for the Solihull 4x4 maker.

But there was better news for Ford-owned sister company Jaguar, where t he push to improve standards is paying off.

Jaguar came eighth. Toyota's luxury Lexus brand ranked highest for the 12th consecutive year in the annual J.D. Power and Associates survey of long-term vehicle dependability.

It is based on responses from 47,620 owners of three-year-old vehicles when questioned about scores of specific problems ranging from wind or brake noise to uneven tyre wear and stalling engines.

The survey is significant for the auto industry because new car buyers say long-term quality is one of the most important factors in their choice of brands. It is also important to automakers because of warranty costs.

Lexus had 136 problems per 100 vehicles. It was followed by Ford's Mercury with 151 problems per 100 vehicles and GM's Buick brand with 153 problems per 100 vehicles.

However, Land Rover was ranked as the least reliable with 438 problems per 100 vehicles, over 100 more than the nearest ranked brand, GM's Saab.

The bitter setback comes despite the much-vaunted "Road Map" at Solihull aimed at improving quality and efficiencies.

Announced in September 2004, it is ongoing.

With rumours abound that Jaguar, Land Rover or both could be offloaded by Ford, the dreadful survey result will not help the latter's cause.

A total of 38 marques were tested.

But the survey has come as a much-needed boost to Jaguar which had 210 problems per 100 vehicles, better than the likes of BMW and Porsche and above the industry average of 227.

Other high-profile European luxury nameplates such as DaimlerChrysler's Mercedes, Ford's Volvo, and Volkswagen's Audi all scored well below the industry average.

BMW's Mini and Hyundai's Kia nameplate saw the largest reduction in problems reported by owners, though both still hovered well below the midpoint.

Overall quality is on the up, another reason why the Land Rover result is such a disappointment.

"The industry continues to make improvements in long-term vehicle quality, and not just among luxury makes that benefit from smaller production volumes on the assembly line," said Neal Oddes, director of product research and analysis for J.D. Power and Associates.

" Many high-volume, mass-marketed brands have acquired a foundation of quality products from which to challenge the normally strong performances of the luxury brands. What this means for consumers is they don't necessarily have to spend a lot of money to get a high-quality used vehicle.

" Perceptions about dependability can have a tremendous impact on an owner's satisfaction with their vehicle."