2008 Pontiac G8 MPG & Specs — Real-World vs EPA, All Trims
It depends on the trim. Some versions take premium and some take regular — check your exact engine/transmission below.
Is the 2008 Pontiac G8 good on gas?
At up to 20 MPG combined, the 2008 Pontiac G8 is about average for a Large Cars — that class averages about 20.3 MPG across 2,605 EPA-tested versions, so it's middle-of-the-road for its size.
Real-world MPG vs the EPA number
The EPA figures above come from a standardized dynamometer test, not the open road — real-world MPG typically runs a bit lower depending on your driving, climate and terrain. That's true of every car on this site, old or new.
At today's AAA national average price — $3.80/gal for regular gas as of 2026-07-05 — the most efficient trim runs about $2,850/year (roughly $238/month, about $19.00 per 100 miles) at the EPA's assumed 15,000 miles/year, using an estimated 750 gallons a year. We don't estimate a cost-per-fill since exact tank size isn't in the public EPA dataset, but the per-100-mile figure scales to any tank. Current national average gas prices →
2008 Pontiac G8 trims & fuel economy
| Trim (engine / transmission) | Fuel | MPG | Fuel/yr (today's price) |
|---|---|---|---|
| 3.6L 6-cyl, S5 automatic, RWD | REGULAR | 20 | $2,850 |
| 6.0L 8-cyl, S6 automatic, RWD | PREMIUM | 18 | $3,900 |
2008 Pontiac G8 specs
What the EPA test-car listings record for this model year — every combination sold is a row in the trims table above.
| Engine options | 3.6L 6-cyl · 6.0L 8-cyl |
| Transmission | S5 automatic · S6 automatic |
| Drive type | RWD |
| EPA body class | Large Cars |
| Fuel | Varies by trim |
Other years of the Pontiac G8
Similar cars (Large Cars)
Cars that take premium · Cheapest cars to fuel · Where fuel grade depends on the trim · Fuel guides
2 trim(s) · EPA FuelEconomy.gov data retrieved 2026-07-24 · fuel prices AAA national average as of 2026-07-05.