CT5 vs IS 350
Cadillac brings the CT5; Lexus answers with the IS 350. Both play in the compact luxury car class. Count the areas and a pattern appears. The CT5 is ahead in 2 of 4, led by a clear margin in fuel economy & range.
At a glance
- Engine & Performance IS 350 wins
- Fuel Economy & Range CT5 wins
- Space & Practicality CT5 wins
- Off-road & Towing Tie
- Price IS 350 wins
- Engine & Performance5.0
- Fuel Economy & Range5.0
- Engine & Performance8.0
- Fuel Economy & Range0.0
Spec scores (0 to 10) are calculated from manufacturer specs against other models in the same class. See how the formula works. They are not reviews or user ratings.
Key Differences
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The IS 350 has 74 hp more power
It’s a lopsided result (311 hp for the IS 350, 237 hp for the CT5) and one of the main reasons to choose between them. More power helps with merging, overtaking and climbing hills, especially with passengers and luggage on board.
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The CT5 has better fuel economy
The spread here is large: 26 mpg on the CT5 versus 22 mpg on the IS 350. Expect to notice it. Official figures rarely match real-world driving exactly, but the ranking between two cars tends to hold.
-
The CT5 has 10% more cargo space
On paper, the CT5 is a touch ahead here, listing 11.9 cu ft against 10.8 cu ft. Cargo figures are measured in different ways by different makers, so small gaps may not show in practice.
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The CT5 has better city fuel economy
Of all the specs we compared, this is one where the CT5 makes its strongest case: 23 mpg against 19 mpg. City fuel economy matters most if your driving is mostly short trips, traffic and stop-and-go commutes.
-
The CT5 has better highway fuel economy
The CT5 clearly leads on fuel economy (highway), and 32 mpg versus 27 mpg is a difference that reaches well beyond the spec sheet. Highway fuel economy matters if you cover long distances at steady speeds.
Design & Size
- CT5 193.8 in × 74.1 in × 57.2 in
- IS 350 185.8 in × 72.4 in × 56.5 in
The CT5 has the bigger footprint. That can mean more room to work with, but also more to carry, park or pocket.
Dimensions
| Spec | CT5 | IS 350 |
|---|---|---|
| Length | 193.8 in | 185.8 in |
| Width (no mirrors) | 74.1 in | 72.4 in |
| Height | 57.2 in | 56.5 in |
| Wheelbase | 116 in | 110.2 in |
Engine & Performance
IS 350 leads
On engine & performance, the gap between these two is wide, and it favors the IS 350. The IS 350 adds 74 hp more power. Power is only part of the story; weight, gearing and torque delivery shape how quick a car feels. Weighing only engine & performance, the IS 350 comes out ahead.
Total system output
CT5: 237 hp IS 350: 311 hp The IS 350’s extra output gives it more in reserve when you need to get up to speed.
Torque
CT5: 258 lb-ft IS 350: 280 lb-ft More torque means stronger pulling from low speeds, which you feel when accelerating from a stop or climbing grades.
Fuel Economy & Range
CT5 leads
The CT5 wins the fuel economy & range section decisively. The CT5 has the edge with better fuel economy. Better combined fuel economy lowers your running costs every week, and the savings add up over years of ownership. If this section decides it for you, choose the CT5.
Fuel economy (combined)
CT5: 26 mpg IS 350: 22 mpg The CT5 uses less fuel on the standard combined cycle, which matters most if you drive a lot.
Fuel economy (city)
CT5: 23 mpg IS 350: 19 mpg Hybrids often shine in the city, and the CT5 has the better rating here.
Space & Practicality
CT5 leads
On balance, the CT5 leads the space & practicality section, just not by much. The CT5 makes its case with 10% more cargo space. Cargo space behind the rear seats is what you use every day for groceries, strollers and luggage. If space & practicality is your priority, the CT5 is the car to pick.
Cargo (behind rear seats)
CT5: 11.9 cu ft IS 350: 10.8 cu ft The CT5’s larger cargo area makes family trips and big shopping runs easier.
Off-road & Towing
Too close to call
This is a tie in all but name. On off-road & towing, both deliver about the same. So off-road & towing is a non-factor here; move on to the areas where they actually differ.
Safety & Tech
There isn’t a number to compare on safety & tech, just names. Look at the rows below to see how the CT5 and the IS 350 differ.
Full Specifications
Engine & Performance
| Spec | CT5 | IS 350 |
|---|---|---|
| Powertrain | Gas | Gas |
| Engine | 2.0L turbo I4 | 3.5L V6 |
| Total system output | 237 hp | 311 hp (winner) |
| Torque | 258 lb-ft | 280 lb-ft (winner) |
| Transmission | 10-speed automatic | 8-speed automatic (6-speed automatic with AWD) |
| Drivetrain | RWD (AWD available) | RWD (AWD available) |
Fuel Economy & Range
| Spec | CT5 | IS 350 |
|---|---|---|
| Fuel economy (combined)EPA estimate where available | 26 mpg (winner) | 22 mpg Thirstiest in class |
| Fuel economy (city) | 23 mpg (winner) | 19 mpg Thirstiest in the city |
| Fuel economy (highway) | 32 mpg (winner) | 27 mpg Thirstiest on the highway |
| Fuel tank | N/A (not specified) | 17.4 gal |
Space & Practicality
| Spec | CT5 | IS 350 |
|---|---|---|
| Seats | 5 seats | 5 seats |
| Cargo (behind rear seats) | 11.9 cu ft (winner) | 10.8 cu ft |
Off-road & Towing
| Spec | CT5 | IS 350 |
|---|---|---|
| AWD / 4WD available | Yes | Yes |
Safety & Tech
| Spec | CT5 | IS 350 |
|---|---|---|
| Largest touchscreen | N/A (not specified) | 12.3 in |
| Basic warranty | 4 yr / 50,000 mi | 4 yr / 50,000 mi |
Dimensions
| Spec | CT5 | IS 350 |
|---|---|---|
| Length | 193.8 in | 185.8 in |
| Width (no mirrors) | 74.1 in | 72.4 in |
| Height | 57.2 in | 56.5 in |
| Wheelbase | 116 in | 110.2 in |
Price
| Spec | CT5 | IS 350 |
|---|---|---|
| Starting MSRP | $47,595 Priciest in class | $45,500 (winner) |
“N/A” means the manufacturer does not specify the value or we could not confirm it. Figures marked “manufacturer rating” are the maker’s own claims, not our measurements.
Price & Value
The launch prices are close, with the IS 350 just $2,095 below the CT5. Step up by $2,095 to the CT5 and you gain better fuel economy and 10% more cargo space.
Launch prices in the US as of launch; street prices move, so check before you buy.
Which One Should You Buy?
Choose the CT5 if…
- you drive a lot and want lower running costs (26 mpg vs 22 mpg combined)
- you haul strollers, luggage or sports gear every week (11.9 cu ft vs 10.8 cu ft)
- you mostly drive in town (23 mpg vs 19 mpg in the city)
- you want better highway fuel economy (32 mpg vs 27 mpg)
Choose the IS 350 if…
- you want more power (311 hp vs 237 hp)
- you often drive loaded up or with a trailer (280 lb-ft vs 258 lb-ft of torque)
- you don’t need the extras that cost $2,095 more
Also Compared
Frequently Asked Questions
Which is better for most people, the CT5 or the IS 350?
For most people, the CT5 is the stronger choice, unless you need 74 hp more power, which only the IS 350 offers.
Which is larger, the CT5 or the IS 350?
Size goes the other way: the CT5 is larger (193.8 × 74.1 × 57.2 in), and the IS 350 is the smaller option (185.8 × 72.4 × 56.5 in).
Is the CT5 cheaper than the IS 350?
The IS 350 is the cheaper option, launching at $2,095 less than the CT5 (launch prices as of launch).
Executive Summary
Cadillac makes the CT5, Lexus makes the IS 350, and both want the same spot on your shortlist. Here’s where I land. Practically speaking, the CT5’s biggest advantage is better fuel economy. Beyond that, 10% more cargo space gives the CT5 another edge. The IS 350 has a trump card of its own in 74 hp more power.
Who should get which? The CT5 for fuel economy & range, the IS 350 for engine & performance.
My pick: the CT5; the one scenario where I’d reach for the IS 350 is if you’d trade the rest for 74 hp more power.
Personal opinion based on the data above. Your priorities may differ.