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GM's fullsize SUVs boost highway mileage by nearly 10 percent

We met the redesigned 2015 versions of the Chevrolet Suburban and Tahoe, and the GMC Yukon and Yukon XL at the 2013 LA Auto Show. Improved gas mileage numbers have been announced to go along with the improved exteriors and interiors, with city mileage improving by seven percent and highway mileage going up by nearly ten percent; you'll now get 16 miles per gallon in the city and 23 on the highway.
The only applies to models with the 5.3-liter engine, though, not the premium Yukon Denali and Yukon XL Denali SUVs with the 6.2-liter motor. Still, the 5.3 gets you more power than previously, with 355 horsepower and 383 pound-feet of torque underfoot, on top of the improved fuel economy numbers. The 6.2-liter sticks with official mpg ratings of 15 highway, 21 city. There's a brief press release below with words straight from the horse's mouth.

Supercharged 2015 GMC Yukon Denali sounds evil, runs 0-60 in 4.5 seconds

Speeding along in a sports car is undoubtedly a ton of fun, but some owners need the ability to carry a lot of people and their stuff and don't want to sacrifice the ability to put the power down. The tuners over at Hennessey have that demographic covered with their growling, supercharged power kits for the GMC Yukon Denali. The upgrades come in three forms for the SUV's 6.2-liter V8: HPE550 with 557 horsepower, HPE600 with 605 hp and HPE650 with 665 hp. This video showcases the full-bore version, and this Denali can definitely hustle in a straight line. The power bump comes courtesy of a 2.9-liter supercharger, intercooler and high-flow cylinder heads to add over 200 horsepower compared to stock, and the final result is a bellowing SUV that rears up off he line to throw the driver back into the seat. The sprint to 60 miles per hour lasts just 4.5 seconds. Check out this hasty hauler in action in the video above.

GM warning 800,000 owners that their cars may need oil changes more frequently than they say

The days of changing your engine oil every 3,000 miles are long gone thanks to most cars having automatic oil monitoring systems, but about 800,000 General Motors vehicles apparently have incorrect monitoring software that is leading to premature engine component wear. According to Autoweek, certain 2010-2012 Buick LaCrosse, Regal, Chevrolet Equinox and GMC Terrain models equipped with 2.4-liter four-cylinder engines could be going too long in between oil changes resulting in a higher-than-normal number of warranty claims for the engine's balance chain. The balance chain links the balance shaft to the crankshaft, and a worn one can produce higher noise levels.
As a fix, GM dealers will be reprogramming the software for the monitors in an effort to reduce the interval between oil changes, which varies based on driving habits and conditions. Through February 2015, the software update will be done at no cost to vehicle owners, but since this is not a recall, after that point, it will be up to the discretion of dealers as to whether or not they will charge for the service. What isn't immediately clear is whether GM plans on giving assistance to out-of-warranty customers who are experiencing engine issues from the worn chain.