All-new 2018 GMC Terrain: Gas or Diesel First Drive Review

2018 gmc terrain awd crossover turbo gas diesel comparison
2018 GMC Terrain: turbo gas or diesel?

2018 GMC Terrain represents the complete redesign and the second generation of company’s compact crossover. The original Terrain showed up on the market in 2009. Nine years is a very long time in automotive years. Does the all-new Terrain have what it takes to remain popular?

The new crossover features sleek styling, it’s a little smaller on the outside, and it has lost up to 350 lbs when compared to the outgoing model. Gone is the old V6 engine. GMC is using a trifecta of turbocharged four-cylinder engines to power the new Terrain. There are two gasoline turbo options and one turbo-diesel. Which one would you choose? Here is a first take on the 1.5L turbo-gas versus the 1.6L turbo-diesel.

2018 GMC Terrain

There are four trim levels of the Terrain: SL, SLE, SLT, and Denali. Things kick off with the base SL model, which is only available in front-wheel-drive configuration and with the 1.5L turbo-4. This model starts at $25,970. The 1.6L diesel is only available in SLE or SLT trims, but you can configure it with front or all-wheel-drive.

The most luxurious and expensive terrain is the Denali AWD with all of the options. It tops out near $45,000, but we will have a more in-depth review of the Denali version separately.


1.5L turbocharged gasoline engine: 170 hp and 203 lb-ft of torque, paired with a 9-speed automatic.

1.6L turbocharged diesel engine: 137 hp and 240 lb-ft of torque, paired with a 6-speed automatic.

2,0L turbocharged gasoline engine: 252 hp and 260 lb-ft of torque, paired with a 9-speed automatic.

2018 gmc terrain real world mpg diesel highway result

This review focuses on the comparison of the 1.5L and the 1.6L engine options. The classic gas versus diesel trade off is the additional initial cost versus the long-term efficiency benefits. The turbo-diesel option in the Terrain will set you back $3,770 in the SLE trim and $2,845 in the higher level Terrain SLT.

What is the fuel economy? The Terrain AWD with the 1.5L turbo is rated at 24/28/26 MPG (city/hwy/combined). The AWD model with the 1.6L diesel is rated at 28/38/32 MPG. That is a considerable difference, and my first drive highway MPG test yielded 38.2 MPG after 47.5 miles (according to the trip computer, not verified at the pump).

GMC says that gas versus diesel maintenance costs are about the same, so this is not enough to sway the decision in either direction. The diesel does require Diesel Exhaust Fluid (DEF), but this is relatively inexpensive and can generally be handled in way similar to an oil change interval.

Driving Experience

The other part of the gas versus diesel is the driving experience. The seat of the pants acceleration in the 1.5L and the 1.6L feels about the same. Both will chirp the tires in front-wheel-drive mode, but the experience is bit different. The 9-speed in the gasoline version shifts quickly after the engine reaches close to 5,500 rpm under full throttle. Several gears are dispatched in quick succession. The 6-speed in the diesel lets the engine rev to about 4,000 rpm before making a quick shift. Each transmission is well-matched to the respective engine. The diesel is still the champion highway cruiser. It rarely needs to shift as the low-end torque pushed the vehicle along.

2018 gmc terrain transmission push button control

All transmission choices share the same push/pull-button transmission control system that is mounted at the lower part of the center console. Why redesign the shifter? GMC says it frees up the center console for more storage space, which is indeed the case. After two hours behind the wheel, I got used to “R” reverse and “D” drive pull switches. If you put your index and middle fingers over the two switches, it’s easy to remember which one is which and shift quickly. The same cannot be said for the “P” park and “L” lower gear range selector. You have to look down to the console to find the park and low gear buttons.

There is a Park shift safety mechanism. If you come to a complete stop, open the driver door, and release the brake pedal – the Terrain will automatically shift into Park for you. If you on an incline, the car will automatically engage the parking brake as well.

Fold-flat front passenger seat


The Terrain still packs a lot of utility. The cargo area holds 29.6 cu-ft of volume behind the rear seats. Fold down the second row and access 63.3 cu-ft of space. If you have an item that is about 8-feet long, then you also fold the front passenger seat and access a total of 81.0 cu-ft of cargo volume. This is very competitive for the compact crossover segment.

2018 GMC Terrain Denali

The 1.5L and the 1.6L model are rated to tow up to 1,500 lbs. If you want to tow a bit more, then the 2.0L turbo is the ticket with a rating of 3,500 lbs.


The Terrain bridges the gap between the mainstream crossovers, such as the Ford Escape, Honda CR-V, and the Toyota RAV4; and the more premium entries from Acura, Audi, BMW, Infiniti, Lexus, and Mercedes-Benz. The Terrain pricing structure spans between $26,000 – $45,000.


My faith in diesel passenger vehicles has recently been shaken by several emissions scandals. I have been a diesel fan in the past. When faced with a choice between the 1.5L turbo-gas and the 1.6L turbo-diesel, I would go for the diesel. The diesel Terrain is just as quiet as the gas version. The engine produces a slightly deeper tone under acceleration, which I like. The gasser may have a slight edge in slow stop-n-go traffic, but the diesel is still king of highway cruising. I would definitely go for the diesel for a road trip.