Before 2006, Mercedes built its M Class SUV on a truck frame. Now the Mercedes ML350 is built on a unibody chassis, which has been used primarily on cars. This brings up a question: Is the Mercedes ML350 a car or a truck and, by extension, are the other unibody SUVs cars or trucks? (See exhibit 1 below for a list of unibody SUVs that Wikipedia and other sources call “crossover vehicles.”)

Why does this question matter? Because, if the Mercedes ML350 is a car, qualifying for section 179 expensing (limited to $25,000 on an SUV) is far more difficult. Here’s why:

With the car classification, tax law counts the unloaded (curb) weight of the car.1

With the truck classification, tax law counts the loaded weight (technically called the gross vehicle weight rating, or GVWR), which includes2

the weight of the truck;

the weight of the people who ride in the truck (standard weights, not all the people you could pack in); and

the weight of the cargo.

In the car classification, the SUV’s curb weight must exceed 6,000 pounds to qualify for section 179 expensing of up to $25,000. (The ML350 has a curb weight of 4,819 pounds; therefore, in the car classification, the ML350 SUV fails to qualify for expensing.)

Almost no cars pass this curb-weight test. For example, the really big 2006 Rolls-Royce Phantom Sedan has a curb weight of only 5,577 pounds.3

In the truck classification, the GVWR of the SUV must exceed 6,000 pounds to qualify it for expensing of up to $25,000. (The ML350 has a GVWR of ... Log in to view full article.