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Looking Back at a Year With a 2017 GMC Sierra 3500

Aug 31, 2018 / by Mark Williams

Looking Back at a Year With a 2017 GMC Sierra 3500

Posted by Mark Williams | August 31, 2018

By Matthew Barnes

We've had a 2017 GMC Sierra 3500 SLT 4x4 crew-cab long-bed for a year now, and we've driven it a little more than 16,000 miles. During that time, we have towed nearly 14,000 miles — mostly in the mountains at elevations ranging from 4,600 feet to 10,000 feet — with loads varying from 10,000 pounds to the truck's rated maximum of 17,000 pounds.

Despite being worked hard, climbing steep grades at high elevations in 100-degree temps, the heavy-duty pickup truck never left us stranded. It was completely reliable; we even used it to rescue a medium-duty truck when it was stranded. We did have a repeat of a hose clamp failure that caused us to lose coolant early in this long-term test. This time we corrected the issue with a screw-type hose clamp, which has more clamping force than the spring-type the truck came with. So far, the issue hasn't returned.

Smooth Sailing on the Road

The transmission smoothed out significantly as the software learned our driving style, with the only noticeably hard shift nowadays being from 1st to 2nd gear on occasion. The interior is still quiet and squeak-free. There are no leaks or rattles, and apart from being a little dirty, the interior of the truck still looks brand new. The IntelliLink infotainment system never froze or gave us any problems connecting via Bluetooth to our phones, which is impressive considering that we've tested similar vehicles that didn't make it through a week without an infotainment issue.

The exterior now wears some tar from road construction; there's a small dent on the rear bumper from rolling back into a trailer tongue; and the pin hole in the trailer hitch receiver has been stretched significantly from heavy towing. Other than that, the exterior seems to have held up nicely through its single winter on salted roads with no visible rust spots on the frame.

On road, the GMC Sierra 3500 has proved smooth, quiet and powerful. The independent front suspension prevented a lot of the side-to-side movement we've experienced with solid-axle heavy-duty trucks. Larger bumps and potholes could upset the rear and jar passengers, but we expect that in a one-ton truck. The steering remained tight and precise. Predictable and consistent braking feel and a linear throttle made driving the truck a breeze. In the limited amount of off-road driving we've done (mainly rutted dirt roads and access lots), we really felt the stiff rear suspension and there was a bit of wheel hop on loose surfaces when we weren't careful with our speed.

Mileage Results

We averaged 11.8 mpg over 16,000 miles in this Sierra 3500, which isn't bad considering that nearly 90 percent of those miles were done while towing heavy loads on steep grades. Our best empty 25-mile run was 34 mpg; that was descending from a mountain top unloaded with a lot of coasting going on. According to our trip computer, on flat roads and highways, in an empty truck, we returned 22 mpg with an average speed of 68 mph.

The four-wheel-drive system was used only a handful of times and only once on rough terrain without a trailer; otherwise, it was used in rain and snow on steep grades for extra traction. Four-wheel-drive low range was used once for better grip and gearing to pull a 17,000-pound trailer slowly up and around a tight curve on a steep 20 percent grade. The extra gearing of the low range always engaged and disengaged quickly and smoothly (with its signature clunking sound and feel), and we were glad that the 2017 GMC Sierra 3500 came equipped with it.

Our Mystery

We did have one anomaly during this first year with the Sierra 3500. It was with the traction control system, which prevented the truck from slowing down on one trip. We were descending a 6 percent grade covered in snow and the truck was in 4WD High with Tow/Haul mode engaged, the diesel exhaust brake engaged and traction control on. Approaching a moderate right-hand curve, the brakes were applied, causing the anti-locking system to activate. Rather than slow down, something in the traction control system caused the truck to keep its speed. To regain control, we left our foot off the brakes and we used the trailer brake controller to slow vehicle and load for the approaching corner. A short time later, we tested the same scenario on a straight section of road and had the same thing happen. Unfortunately, we couldn't replicate the situation later, but it could have been dangerous had we not allowed significant braking distance for the corner. We have contacted GMC regarding the issue and are working to find out what could have made this happen. We'll pass that along once we find out more.

We were never able to get a clear answer from GMC about why this Sierra 3500 slightly leans to the driver's side when viewed from the rear, but that never affected the driving dynamics of the truck and hasn't affected tire wear.

Summing It Up

Overall, we have really enjoyed driving this 2017 GMC Sierra 3500. It will stay in our fleet for years to come, allowing us to provide a true long-term test of the vehicle. We look forward to wearing out many more sets of tires and brakes and seeing how the truck holds up to our heavy use and abuse.

Here's what our 2017 GMC Sierra 3500 has cost us to date (in addition to the $67,270 price of the truck):

Operating Expenses: