2018 Cadillac CT6 Gas Tank Size & Fuel Capacity
Fuel tank capacity
15.6–19.5gal · 59–74 L
The 2018 Cadillac CT6 has a fuel tank capacity of 15.6 to 19.5 gallons (59–74 liters), depending on the trim. The most common size is 19.5 gallons, used on 9 trims.
A full tank is good for roughly 452–585 highway miles or 351–429 miles around town, going by the EPA ratings.
19.5 gal · Bigger than 65% of 2018 models we list.
- By trim
- Gas cap & parts
- Fuel essentials
- Miles per tank
- Fill-up cost
- Other years
- Compared
- Pump & gauge parts
- FAQ
2018 Cadillac CT6 fuel tank capacity by trim
What changes the tank sizeTap an option to filter the table
- Powertrain
- Drive
- Engine
All 10 trims
MPG and range are city / highway.
| Trim | Engine | Drive | Tank | Fuel | MPG city / hwy | Range city / hwy |
|---|---|---|---|---|---|---|
| PLUG-IN 4dr Sedan 2.0L 4cyl Turbo EVT · RWD · Premium (recommended) Plug-in hybrid MPG 23 / 29Range 359 / 452 mi | 2.0L 4cyl Turbo EVT Plug-in hybrid | RWD | 15.6 gal59 L | Premiumrecommended | 23 / 29 | 359 / 452 mi |
| 4dr Sedan 2.0L 4cyl Turbo 8A · RWD · Premium (recommended) MPG 22 / 30Range 429 / 585 mi | 2.0L 4cyl Turbo 8A | RWD | 19.5 gal74 L | Premiumrecommended | 22 / 30 | 429 / 585 mi |
| 4dr Sedan AWD 3.6L 6cyl 8A · AWD · Regular MPG 18 / 27Range 351 / 527 mi | 3.6L 6cyl 8A | AWD | 19.5 gal74 L | Regular | 18 / 27 | 351 / 527 mi |
| Luxury 4dr Sedan 2.0L 4cyl Turbo 8A · RWD · Premium (recommended) MPG 22 / 30Range 429 / 585 mi | 2.0L 4cyl Turbo 8A | RWD | 19.5 gal74 L | Premiumrecommended | 22 / 30 | 429 / 585 mi |
| Luxury 4dr Sedan AWD 3.0L 6cyl Turbo 8A · AWD · Premium (required) MPG 18 / 26Range 351 / 507 mi | 3.0L 6cyl Turbo 8A | AWD | 19.5 gal74 L | Premiumrequired | 18 / 26 | 351 / 507 mi |
| Luxury 4dr Sedan AWD 3.6L 6cyl 8A · AWD · Regular MPG 18 / 27Range 351 / 527 mi | 3.6L 6cyl 8A | AWD | 19.5 gal74 L | Regular | 18 / 27 | 351 / 527 mi |
| Platinum 4dr Sedan AWD 3.0L 6cyl Turbo 8A · AWD · Premium (required) MPG 18 / 26Range 351 / 507 mi | 3.0L 6cyl Turbo 8A | AWD | 19.5 gal74 L | Premiumrequired | 18 / 26 | 351 / 507 mi |
| Platinum 4dr Sedan AWD 3.6L 6cyl 8A · AWD · Regular MPG 18 / 27Range 351 / 527 mi | 3.6L 6cyl 8A | AWD | 19.5 gal74 L | Regular | 18 / 27 | 351 / 527 mi |
| Premium Luxury 4dr Sedan AWD 3.0L 6cyl Turbo 8A · AWD · Premium (required) MPG 18 / 26Range 351 / 507 mi | 3.0L 6cyl Turbo 8A | AWD | 19.5 gal74 L | Premiumrequired | 18 / 26 | 351 / 507 mi |
| Premium Luxury 4dr Sedan AWD 3.6L 6cyl 8A · AWD · Regular MPG 18 / 27Range 351 / 527 mi | 3.6L 6cyl 8A | AWD | 19.5 gal74 L | Regular | 18 / 27 | 351 / 527 mi |
| No trim matches all of these filters. | ||||||
Tank figures are the manufacturer's rated capacity, sorted smallest tank first. Range is tank size times EPA city or highway MPG.
How far a 2018 Cadillac CT6 goes on a tank
Gallons left and the distance they cover at each mark on the fuel gauge, at EPA city and highway mileage. At the combined rating of 21 MPG, a full 19.5-gallon tank covers about 410 miles.
| Gauge | Gallons | Highway miles | City miles |
|---|---|---|---|
| Full | 19.5 | 527 | 351 |
| 3/4 | 14.6 | 395 | 263 |
| 1/2 | 9.8 | 263 | 176 |
| 1/4 | 4.9 | 132 | 88 |
| 1/8 | 2.4 | 66 | 44 |
Over 15,000 miles a year (the EPA's yearly estimate) this configuration uses about 714 gallons, roughly 37 full tanks.
Fuel gauges aren't perfectly linear and the low-fuel light comes on with a few gallons still in the tank, so plan your stop before the last eighth.
- EPA combined
- 21–25 MPG
- Tailpipe CO2
- 144–424 g/mi
- EPA greenhouse score
- 4–10 of 10
- Source
- EPA ratings
What it costs to fill up a 2018 Cadillac CT6
$102.96 to fill the 19.5-gallon tank from empty with premium, at this week's US average of $5.28 a gallon.
| Tank | Fuel | US avg / gal | From empty | From 1/4 tank |
|---|---|---|---|---|
| 15.6 gal | Premium | $5.28 | $82.37 | $61.78 |
| 19.5 gal | Premium | $5.28 | $102.96 | $77.22 |
| 19.5 gal | Regular | $4.27 | $83.26 | $62.45 |
By region, 19.5-gallon tank
| Region | Premium / gal | Fill from empty |
|---|---|---|
| East Coast | $4.93 | $96.13 |
| Midwest | $5.37 | $104.72 |
| Gulf CoastLowest | $4.57 | $89.12 |
| Rocky Mountain | $5.12 | $99.84 |
| West Coast | $6.08 | $118.56 |
| CaliforniaHighest | $6.36 | $124.02 |
Prices: U.S. Energy Information Administration retail averages for the week of October 26, 2026. This week's prices by state and city.
Your own price
- 15.6-gallon tank$82.37
- 19.5-gallon tank$102.96
- A year of driving (15,000 mi)$3,771
Starts at the US average for premium; type in what your station charges. For other tank sizes, use the fill-up calculator.
CT6 tank size in other years
The 2018 CT6 uses the same 15.6–19.5 gal tank sizes as the 2017 model.
| Model year | Tank | Longest highway range |
|---|---|---|
| 2020 CT6 | 19.2 gal | 518 mi |
| 2019 CT6 | 19.5 gal | 663 mi |
| 2018 CT6 | 15.6–19.5 gal | 585 mi |
| 2017 CT6 | 15.6–19.5 gal | 585 mi |
2018 Cadillac CT6 vs similar 2018 sedans
At 19.5 gallons, the CT6's largest tank ranks third of the four 2018 sedans compared here. The Porsche Panamera carries the most (23.7 gal) and the Lincoln Continental the least (18.0 gal).
| 2018 model | Tank | Longest highway range |
|---|---|---|
| Porsche Panamera | 21.1–23.7 gal | 664 mi |
| Jaguar XJ | 21.7 gal | 586 mi |
| Cadillac CT6 | 15.6–19.5 gal | 585 mi |
| Lincoln Continental | 18.0 gal | 486 mi |
Other 2018 sedans of a similar size, one model per brand.
2018 Cadillac CT6 fuel pump and gauge parts
These are the part numbers the makers list for the 2018 Cadillac CT6. Check the fuel system recalls first: recall repairs are free.
As an Amazon Associate we earn from qualifying purchases.
Frequently asked questions
What is the fuel tank capacity of the 2018 Cadillac CT6?
The 2018 Cadillac CT6 holds between 15.6 and 19.5 gallons, depending on the trim. 19.5 gallons is the usual size; the smaller 15.6-gallon tank is on the PLUG-IN 4dr Sedan.
How many gallons and liters does the 2018 Cadillac CT6 gas tank hold?
The 2018 Cadillac CT6 tank holds 59–74 liters, or 15.6–19.5 gallons in US gallons.
Which 2018 Cadillac CT6 has the biggest gas tank?
The 19.5-gallon tank is on the 4dr Sedan, 4dr Sedan AWD, Luxury 4dr Sedan and 6 other trims. The smallest tank, 15.6 gallons, is on the PLUG-IN 4dr Sedan.
Does the 2018 Cadillac CT6 tank change with the powertrain?
Yes. Plug-in hybrid: 15.6 gal; Gas: 19.5 gal.
Does AWD change the 2018 Cadillac CT6 gas tank?
Yes. RWD: 15.6–19.5 gal; AWD: 19.5 gal.
How far can a 2018 Cadillac CT6 go on a full tank?
About 452–585 miles on the highway and 351–429 miles in town, going from full to empty at its EPA ratings. Expect less in practice, since nobody runs the tank dry.
How many miles can a 2018 Cadillac CT6 go on a quarter tank?
About 132 highway miles or 88 in town from the 19.5-gallon tank, which has roughly 4.9 gallons left at the quarter mark. Gauges aren't exact, so treat that as a guide.
What gas does the 2018 Cadillac CT6 take?
Regular unleaded, or Premium unleaded (recommended), or Premium unleaded (required), depending on the engine. The label inside the fuel door confirms it for your car.
How much does it cost to fill up a 2018 Cadillac CT6?
At the US average of $5.28 a gallon for premium (EIA, week of October 26, 2026), filling the 19.5-gallon tank from empty costs $102.96. It ranges from $89.12 in the Gulf Coast to $124.02 in California.
How much does a full tank of gas weigh in a 2018 Cadillac CT6?
About 121 pounds for the 19.5-gallon tank. Gasoline weighs roughly 6.2 pounds a gallon.
Does the 2018 Cadillac CT6 have a bigger gas tank than the Jaguar XJ?
No. The 2018 Jaguar XJ holds up to 21.7 gallons; the 2018 Cadillac CT6 holds up to 19.5.
Sources
- Tank sizes: manufacturer-rated capacities from US-market specifications, checked against independent references. Updated October 2026.
- MPG and range: EPA ratings (fueleconomy.gov). Range is tank size times EPA MPG.
- Fuel prices: U.S. Energy Information Administration, week of October 26, 2026 (this week's prices).
Does your owner's manual say something different? Let us know and we'll fix it. More on how we check the numbers.