(Ask TFL) 2020 GMC Sierra 1500: Should I Buy a 6.2L V8 Gas or a 3.0L Diesel?

The fuel cost is actually about the same!

2020 GMC Sierra 1500 AT4
2020 GMC Sierra 1500 AT4

Should I buy a new 2020 GMC Sierra 1500 with a 6.2-liter gas V8 or a 3.0-liter turbo-diesel I6? We recently received this question from Gerry, a TFLtruck viewer.

I’m looking to get a 1500 Sierra. I’m not sure if I should get the 6.2 gas or the 3.0 Duramax. I do some towing, but nothing too heavy. Is the higher fuel mileage worth the higher price diesel fuel? Will I notice the lesser horsepower in the Duramax.” – Gerry B.

2020 GMC Sierra 1500

New trucks offer more engine options than ever. It’s becoming ever more difficult to make a choice. Our goal at TFLtruck is to show you how different trucks perform in the real world, and make the choice more clear.

Let’s quickly look at the engine stats. Both the gas 6.2-liter V8 and the diesel 3.0-liter I6 are offered by GM at the same retail price. Both engines are mated to a 10-speed automatic transmission. The biggest differences come in terms of power delivery and fuel economy.

The 6.2-liter V8 is rated at 420 hp and 460 lb-ft of torque, and the fuel economy is rated with premium gasoline. This is important. The maximum power rating is given with premium fuel, which is currently more expensive than the diesel.

Here are the EPA fuel-economy ratings for a Sierra 1500 4×4.

(source: www.fueleconomy.gov)

Naturally, the diesel has a significantly better economy. In the real world, the efficiency difference can be even more significant. We will be doing more testing on this within the next several weeks.

Here are the average fuel prices, according to the AAA.

(source: gasprices.aaa.com)

The mid-grade fuel prices are very similar to the diesel fuel pricing, according to this national average data. You can use the AAA website to lookup fuel price averages for your state or region.

The new 3.0-liter turbo-diesel I6 is rated at 277 hp and 460 lb-ft of torque.

If you put these two trucks (a 6.2-liter V8 and a 3.0-liter I6) in a drag race against each other – the two may take launch at about the same rate, but the V8-powered truck will continue to gain the speed faster. The gas truck will win the race, based on peak horsepower.

If you need to tow over 8,500 lbs, and if you love that gas V8 sound – then go for the gasser. If you are not towing very heavy and plan to put a lot of miles on the truck – then the diesel may be a better choice.

One other thing to remember is maintenance costs. We do not yet know the real-world longevity and reliability of the new 3.0L Duramax. Also, the diesel oil changes and most diesel services will cost more than those for the gas engine.

You will also have to refill the DEF fluid once or twice per year (depending on how many miles you drive).