WASHINGTON — This week we switch to the biggest ride we’ve tested so far — one that just barely fits in the garage here at WTOP.

The all-new 2015 Sierra 2500 HD double cab gains regular rear doors instead of the old extended cab where the front doors had to open for the back ones to open. This is definitely a plus in my book.

I drove around in a $62,525 2015 Sierra 2500 HD with the SLT trim level, meaning it was loaded and it even had the big turbo diesel option. It’s a pricey $7,195 option at that, and also requires a $1,200 Allison automatic transmission that helps deal with 397hp and 765 pounds per feet of torque.

The base engine is still a healthy 6.0 liter gas V8 and there is even an option to add compressed natural gas to your gas V8 and have a bi-fuel model. If you have never looked at the build- your-own model on the GMC or any truck for that matter there are many ways to equip a truck, from the cab size to the rear bed length and many other options.

The new HD or full-size trucks from GM have been given a big makeover now that the GMC and Chevrolet look different. As a Chevy truck guy, I have to admit I now prefer the GMC look. The GMC has a bolder look to it and it stands out. The outside is very nice but the interior and ride is where the biggest improvement lies. The interior isn’t just nice for an HD truck, it’s nice for any vehicle and more in line with the redesigned light duty trucks from GM — a vast improvement.

The inside is quiet and the heated and cooled seats are comfortable. The back seats can be tight with a rear facing car seat; there is a larger crew cab with a larger passenger cabin.

The NAV is huge improvement over the previous trucks. If you have the DVD NAV from 2013 or before, you know what I mean.

The ride is better than the past models of HD trucks and even some light duty trucks. There is some bounce on bigger bumps and rough pavement with an empty bed. But that’s to be expected on something that can hold 3,000 lbs. in the back bed or tow up to 13,000 lbs. with a hitch or over 17,000 lbs. fifth wheel. I loaded the bed several times and the bounce goes away. Hooking to the trailer is easy and doesn’t require anyone’s help because of the rear-view camera. The camera would have made old trailer towing days much easier.

Driving the big GMC Sierra HD was surprisingly easy. Only on the narrow part of Connecticut Avenue inside Maryland, do you notice the size — it takes up most of the lane. I was really bitten by the diesel bug. The 765 pounds of torque is great and after a few minutes I was hooked to the power. Luckily the heavy duty brakes are also powerful. Fuel economy isn’t applicable to the HD trucks but I was surprised by 15.2 mpg in 241 miles of city commuting and a little highway driving and a few trips with a full bed.

The new 2015 GMC Sierra 2500 HD double cab 4×4 is a very good heavy duty truck that is just as happy at construction sites as it is carting the family on vacation. You can even tow your home away from home and skip the hotels. With different trim levels, bed lengths, engines and cab sizes, there is a truck for most anyone looking for a more refined capable truck for all their needs.

I really don’t have the amount of work for an HD truck with diesel but after a week with the GMC, I wish I did.

Editor’s note: Mike Parris is a member of the Washington Automotive Press Association. The vehicles are provided by STI, FMI or Event Solutions for the purpose of this review.