There are milestones and then there are "million milestones."

With the economy still wobbly for many folks, there are some vehicle owners not only delaying purchase of a new vehicle but trying to surpass all expectations for how long they cam make their current wheels last.

And for a handful of pickup owners, adding a seventh figure--yes, more than a million miles-- to their odometer is all in a days work. A million miles is more than a big deal. It’s like driving to the moon and back twice and still having 97,512 miles to go. On a more realistic basis, it would take 10 years, driving 273 miles every day to hit the million mile mark.

Gary Mueller was told by his friends to get a new truck when his 2002 F-350 Super Duty hit 300,000 miles. But he didn’t listen, and now, he’s got 1,020,000 miles on his truck.

“This truck isn’t just a truck; it’s an extension of me,” said Mueller. “I take care of it and it returns the favor. I see no reason at all to think about retiring it.”

Mueller, who retired from Ford in 2000, had planned on traveling around North America and enjoying his retirement. But when he lost nearly 70 percent of his investments, he had to find a way to supplement his income.

That’s when he started hauling recreational vehicles and campers, delivering to them to customers around the country. For the past 10 years, he’s visited 48 states and seven provinces in Canada. Traveling during his retirement, without actually retiring.

It takes dozens of sets of tires, scores of oil filters, and thousands of gallons of fuel, these million milers say.

“I’ve gone through three water pumps, five alternators, a couple of starters, a U joint and a couple of ball joints,” said Duane Thalen of his 1999 Ford F-250 diesel Super Duty. “Things wear out.”

Thalen, 47 from Grand Rapids, Mich., delivers campers and hauls other things on a weekly basis, averaging more than 600 miles a day Monday through Friday.

“I always make sure I’m home for the weekend,” he said, even as he was driving through Pennsylvania with a boat in tow headed for Minnesota.

“I bought this truck used in 2004 with 100,000 miles on it,” Thalen said. “Now, it’s at 1.2 million miles and just keeps going. It just keeps going.”

Tammie Roeber of Colgate, Wis., has managed to drive 1.2 million miles in just six years.

“I signed the papers on my new GMC Sierra 3500HD one-ton pickup in 2006, hitched up a trailer, and have been on the road since,” said Roeber, who makes a living hauling horses around the Eastern United States.

Much of the time, Roeber pulls a 48-foot long 16,000 pound trailer that can carry up to nine horses.

She changes the oil every 15,000 miles, or about every three weeks.

Obviously, good maintenance is going to help keep pickup trucks on the road. But it also helps if they are built right in the first place. J.D. Power and Associates every year ranks vehicles according to reliability and dependability--how well the vehicles have performed over three years of ownership.

Check out the best pickup models, and see which one is the top ranked for reliability over three years of hauling and driving:

The Chevy Silverado beats out its arch nemesis Ford F150 in the JD Power survey of owners. Ford is the top selling truck brand in the U.S., and has been for many years. But General Motors, between Silverado and its GMC Sierras actually sells more pickup trucks each year.

Power representatives interview original owners of those vehicles to find out how many problems they've experienced over the past 12 months. For the 2012 study, J.D. Power spoke to over 31,000 vehicle owners between October and December of 2011.

What does Silverado have to offer besides reliability? It's offered in three different cabs (Regular,Extended,and Crew) and three beds (short,standard,and long). There are 2- and 4-door body styles.

Chevrolet Silverado 1500 standard-duty models are fitted with four different engines. Base models feature a 4.3-liter V-6 engine rated at 195 horsepower. Optional engines include a 4.8-liter V-8 rated at 302 horsepower and a 5.3-liter V-8 rated at 315 horsepower. A 6.2-liter V-8 that produces 403 horsepower is also available. There is also a hybrid,with a 6.0-liter V-8 engine rated at 332 horsepower with two 60-kW electric motors.

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It is not surprising that GMC Sierra nailed the #2 spot for reliability, and is rated very close to Silverado because there are a lot of mechanical similarities between the two as they come from the same automaker--GM.

GMC Trucks traditionally are packaged, promoted and priced as the upper-level pickup. The brand's ad campaign, Professional Grade, has long been intended to target the professional contractor and builder.

What's it got? Base Sierra 1500 models are fitted with vinyl upholstery,air conditioning,trip computer,OnStar telematics,and a basic audio system with CD/MP3 capability. Higher trim levels are rigged with leather upholstery, Bose audio upgrade, remote engine start, and other premium equipment.

GMC Sierra 1500 models are outfitted with one of five engines—including a hybrid. The standard engine is a 4.3-liter V-6 rated at 195 horsepower. Optional powerplants include a 4.8-liter V-8 rated at 302 horsepower and a 5.3-liter V-8 rated at 315 horsepower, as well as a 6.2-liter V-8 that delivers 403 horsepower. Transmissions for the gasoline models are 4- or 6-speed automatics. The optional hybrid gasoline-electric powertrain uses a gasoline-fed 6.0-liter V-8 engine rated at 332 horsepower and two 60-kW electric motors.

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According to J.D. Power, the most reliable truck over three years of ownership is the Toyota Tundra.

One one hand, we should be surprised, but on the other hand--not so much. Toyota has long dominated the Power reliability study with all its cars, SUVs and even its pickup truck.

The Tundra has not been a barn-burner on the sales front. It has only been a few years that Toyota has actually sold what we would call a truly competitive full-sized pickup. But as soon as the company introduced it, the economy, including the home-building industry, tanked.

The current Tundra is Toyota third crack at selling full-sized pickups in the U.S., and it is the closest it has come to offering a serious competitor to Ford, GM and Ram. Truck buyers in the U.S. are fiercely loyal to their brands, so it is a tough market to crack. And while Toyota is racking up accolades on reliability, serious pickup truck buyers who punish their trucks tell us that Ford, GM and Ram still mostly beat Toyota on total capability and toughness.

Still, the numbers are the numbers, and Toyota is off to a good start in winning hearts of pickup truck buyers with solid reliability.

What's it got? Tundra is offered in regular,extended,and crew cab body styles. Eighteen-inch steel wheels are standard,with larger alloy wheels available on higher grades. Base Tundras are fitted with cloth upholstery, dual-zone air conditioning and 4-zone audio system. Higher trim levels include power windows, power locks,leather upholstery, keyless entry, bed tie-down system, and other upscale niceties. Toyota Tundra models are fitted with one of three engines. The standard is a 4.0-liter V-6 engine rated at 236 horsepower mated to a 5-speed automatic transmission. Optional is a 4.6-liter V-8 engine rated at 310 horsepower or a 5.7-liter V-8 rated at 381 horsepower. There is no super-duty diesel.

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