The auto industry has been building motor vehicles in volume for more than a century and, not surprisingly, have taken most aspects of their product to a very high state of the art.

This is particularly true of a number of areas that were problematic in the past. Today's vehicles benefit from design and materials that have dramatically increased resistance to rust, paint from fading and interior vinyl from cracking. Yet despite these improvements, new-car dealers and a host of specialty companies still push a wide range of products designed to offer protection in these areas.

A Megawheels reader who purchased a new car which had already been prepared with a $600 "protection package" asks if these products are really necessary.

"Bottom line, my car looks great. Whether its condition can be attributed to the protection system though may be difficult to say or claim," he says. "I'm considering buying another new car soon. To further protect or not is the question."

It's not an easy one to answer. We talked to a lot of people, most with a vested interest of some kind in the issue, and to be honest, couldn't come up with a definitive answer. We did come up with some food for thought, though.

Car manufacturers boast lengthy rust warranties (at least against perforation) and leave vinyl dashboards and trim exposed in the desert to test their durability. Automotive paint manufacturers claim their products can survive just about anything.

The makers of the various protective products claim things aren't quite that rosy, and if you want to protect likely the second-biggest investment (after a house) you'll make, then you'd better apply some of their potions.

Car dealers are caught in between. They tout the quality of the vehicles they sell, but can't resist the additional profits generated by these products.

At a dealership we queried, you can spend up to $900 on undercoating, rustproofing and fabric and vinyl protection. It already applies a paint-protection product to all its cars (and factors the cost into the purchase price) after experiencing problems with insects in its area.

The salesman said I could buy any combination of the products. The fabric and vinyl treatment listed at $395, but I could get it for $300. What he called undercoating (which involves injecting a substance into interior panels, and which also is claimed to provide a degree of sound and temperature insulation) was another $300 and rust protection, apparently a coating of the complete underside of the vehicle, the engine bay etc., yet another $300.

All jobs are performed by an outside shop, and come with a lifetime guarantee if you keep up with the $25 inspections every two years.

"There's no doubt they are a huge profit centre for dealers. And with manufacturers squeezing their margins, dealers are more and more dependent on service and additional products like these," says a senior technical representative for one auto manufacturer.

"I think the day of rustproofing has come and gone," he says, referring to the rusty Ford syndrome of two decades ago that caused almost an over-reaction in both design and materials to combat rust.

"I doubt there's a manufacturer's product out there that really needs rustproofing any more."

On the other hand, he is a "believer" in protective paint sealants and waxes.

"I think they improve the life expectancy of the paint, reduce [ultraviolet] damage, and help reduce chipping," he says. "And we certainly won't take away anybody's warranty who has had this done."

The tech representative believes protecting the upholstery is a good idea, particularly if you have children or pets in the car. "So I think two out of three of these make sense, as long as the dealer isn't jamming you too much for them," he says.

He does ask that if you're leasing a car and handing it back in three or four years, "why spend the money?" But if you're planning on keeping it for the long term, these products are more desirable.

A detailer I spoke to looks on what he calls "three-ways" rust, paint and upholstery treatments as mainly being ADPs or additional dealer profits. He says rust was an issue in the past, but cars these days come with extensive anti-rust protection, so "why would we want to add more?"

Some of his customers ask for fabric protection, but he says in reality you can do it yourself with a spray can of Scotchguard. "All you're really paying for is the labour."

The detailer is in the business of protecting and beautifying automotive finishes, mostly with more traditional products such as waxes. And he voices, admittedly rather unscientific concerns, that protective coatings may not allow paint to breath and flex properly.

"You've got to look closely at what the manufacturer covers [with warranties] and what this additional $600 bucks is buying me," he says.

On the rust-protection issue, Mario Segreti, general manager of long-established Rust Check Corp., says that while vehicles may have become a lot better, they're still going to rust eventually. So if you're planning on keeping yours for a long time, additional rust protection is still a sound investment.

His company's process uses a petroleum-based product injected into the panels and costs $109 for the initial application and the same amount for an annual treatment. It's like maintaining your engine with oil changes, he says.

It seems a case can be made for some of these protective products, at least for those who plan on keeping their car for a long time, but it also seems some dealers may be selling them at rather outrageous profit margins.

Do your homework on the products offered and then drive a hard bargain with your dealer or shop around to see if you can get a better price elsewhere.