Does it make sense to you that the new car you drive out of the dealer's showroom comes without a spare tire? A lot of people shake their heads but we've all got to get used to it.

The spare tire is disappearing from vehicles in the same manner that cigarette lighters did and it's not because fewer car buyers want them, or the space they take up, it's all because of the weight they add to the vehicle.

Increasing federal regulations have driven the auto industry's obsession with fuel economy while volatile gas prices have directed consumers to look in the same direction... That's what led to the development of the "temporary" compact spare tire in the '80s and those same pressures may now eliminate spare tires entirely, according to the Detroit Free Press.

Auto Critic Mark Phelan reports that the general rule of thumb is that a 10 percent reduction in vehicle weight leads to a 6-7 percent improvement in fuel economy.

Consequently, auto makers are replacing spare tires with tire sealants and an inflation kit to fix most flats. Those items together weigh only about 5 to 6 pounds, compared to 30 lbs. or more for a temporary spare and 50 or more for a full size spare and the necessary tools to change it, says Terry Connolly, GM's director of chassis engineering.

The benefits of reducing that much weight are too great to resist, Phelan says, because a 1 mpg difference in the fuel efficiency for a compact car can save the driver another $50 to $100 annually at the pump, according to the Dept. of Energy.

Most consumers say they're OK with the sealant and inflation kit, as long as they have 24/7 Roadside Assistance, and just about every new car sold offers that. Automakers still provide full-size spares for pickups and SUVs that will be driven off-road. For most other cars, including smaller crossover SUVs the trend is to provide repair kits.

Still, even with Roadside Assistance, if you ever need it, hopefully you'll be able to reach them from your cell phone. (Another reason to have a mobile phone charger in your vehicle!)

What do you think? Would you prefer to have the spare on board or are you OK with sealants and an inflation kit?