Don't overdo it

Personalizing your car is a lot like improving real estate, says MacGillivray. Some modifications will go far in enhancing the value and desirability of your car, others won't. When choosing accessories for your car, make sure the upgrades are appropriate to your vehicle type and that they will appeal to a large number of potential buyers.

Specific improvements are likely to add a greater value on specific makes and models. "For example, if you own a luxury car that doesn't have a sunroof in it, that could actually hurt the resale value of that car more than it would a midsize family sedan like a Toyota Camry, because that kind of upgrade will be something buyers will be expecting to find installed on a luxury car," says Voss.
But Simms warns that a vehicle can cross the line from properly optioned to extremely over-personalized.

You might gain the respect and admiration of a very select group of gear-heads if you lower the suspension on a typical late-model coupe or sedan and add 22-inch rims with ultra-low-profile tires, a stereo system with sheet-metal-rattling bass sound, Lamborghini scissor-style doors and other racy add-ons. You also might attract the attention of every radar cop and speed trap you travel past. But when you sell or trade-in that car it's unlikely you would even get the wholesale or Kelley Blue Book value, despite spending thousands of dollars on so-called "improvements."

Not only do you greatly limit the future marketability of such a car, but also you've likely voided its warranty, says Simms, adding that such alterations also imply that the vehicle was driven hard during its life. "In addition, when we accept a trade-in that has had a lot of intake and exhaust work done on it, there is a concern that it might not pass, in our case, stringent California emissions."

"And with an overly modified car, for example, the way our business runs, we wouldn't be able to retail such a car because we wouldn't be able to offer an extended service warranty on it to our customers," says Voss. "We just wouldn't be able to sell that vehicle on our retail lot because modifying the suspension voids any manufacturer's warranty. We also don't have the ability or luxury to stick a 'for sale' sign on its window and then wait, wait, wait and wait."

The point of diminishing returns varies because every vehicle is different and everybody's taste is different, says MacGillivray. "You really need to do your homework. You need to talk with the installers and shops in your area to get an idea of what will work best and what won't for your particular car -- especially if you are concerned about optioning or modifying your car and then not getting a return on your investment."

When more means less

Inappropriate-size alloy rims/wheels with low-profile tires.

Overpowered stereos, such as units with so-called "kicker-boxes" or enormous bass-speakers in the back of the trunk.

Aftermarket superchargers or turbochargers. This implies car was driven hard or aggressively.

Loud aftermarket exhaust systems.

Lowering/modifying suspensions. This is especially hurtful to late-model vehicles and often voids the manufacturer's warranty.

Low quality or vibrant-colored leather/vinyl/cloth interiors.

Repainting the car in an unusual, non-factory color or a "mystic" finish. This limits the vehicle's appeal, causes problems related to matching paint color/finish at the time of future repairs and can raise questions in a future buyer's mind about why the car had to be entirely repainted)

Simms and Voss agree that upgrades that provide the greatest value are those that are appropriate to your class of vehicle and that are commonly installed as part of factory option packages offered by your vehicle's manufacturer.

Such extras afford the comfort, convenience and value that you can enjoy as an owner -- and which your car's future buyers will likely be looking for.

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