This article is part of a technical review series on the Lexus IS500. On this vehicle, it is using the Toytoa 2UR-GSE V8 engine, mated to the Aisin AA80E transmission.
Let’s skip those information which you can easily find on the internet. We will look at the engine first.
Part 1. The Engine
There are various methods and standards for measuring engine output, particularly for 4-stroke engines. In the U.S., manufacturers commonly use the SAE standard, specifically SAE J1349. However, if an automaker wishes to claim ‘SAE Certified,’ they must also adhere to SAE J2723, which imposes stricter regulations on how correction factors are applied in J1349. As a result, ‘SAE Certified’ ensures less flexibility for automakers to manipulate correction factors, which could otherwise be used to inflate the actual engine output. I would like to call out that, according to the official SAE certification data base, Toyota engines are NOT “SAE Certified”. Toyota may state that their horsepower and torque figures are based on certain SAE standards, but they are not SAE Certified. While it’s perfectly acceptable not to be SAE Certified, it’s important to keep in mind that the claimed “472 hp” for the IS500 should be taken with a grain of salt, as it might not be directly comparable to figures from other automakers. For simplicity, however, I will continue to reference the “472 hp” and “395 lb-ft” figures for the IS500 throughout this article.
For a naturally aspirated engine, one of the most critical parameters for gauging performance is Volumetric Efficiency (VE). VE indicates how effectively an internal combustion engine moves the fuel and air mixture in and out of the cylinders. Naturally, the higher the VE, the better the engine’s output at a given RPM. Quantitatively, VE can be measured by the amount of peak torque the engine produces per unit of displacement, typically expressed as lb-ft per liter (lb-ft/L).
We focus on lb-ft/L instead of peak horsepower because achieving higher peak horsepower can be relatively easier—by using lighter, stronger internal components and raising the redline RPM. In contrast, increasing peak torque is much more challenging, as it is influenced by nearly every aspect of the engine. Factors such as the design of the intake and exhaust manifolds, the cooling system for the engine block and headers, the fuel injection system, valvetrain technologies, and the geometry and structure of components like the pistons, connecting rods, and crankshaft all play a crucial role.
With that being said, let’s compare the 2UR engine with some popular natural aspirated engines (they all have 4 valves per cylinder for fair comparison):
I would like to emphasize that, as shown in the last three columns of the table (Coyote, S54, F136), a well-designed, high-quality performance engine should excel in both power-to-displacement ratio and Volumetric Efficiency (VE). Even if we set lower standards, a performance engine should still stand out in at least one of these areas. For instance, Toyota’s 2ZZ-GE used in the Celica SX may have lower VE, but its power ratio reaches 105.23 hp/L. However, we shouldn’t focus too much on power ratio, as it can be relatively ‘easy’ to improve by increasing the redline RPM. VE, on the other hand, is a more accurate indicator of an engine’s design excellence.
Theoretically speaking the more # of cylinders an engine has, the easier for it to achieve better VE. This is because more pistons means more air intake surface area and therefore beneficial for the engine to “breath”. However the 2UR-GSE even falls behind many V6s with a large margin, which indicates there are significant drawback in its design. In addition, since it gains 3 lb-ft of torque but loses 1hp on the LC500, this also indicates the 2UR engine has reached its full potential for the current architecture: it is not because Toyota has not tried their best or purposefully limit the output, that is indeed the maximum it can achieve by design.
Next let’s evaluate from another aspect. A similar calculation will show the 2UR has a small edge on some common engines such as Honda’s J35 V6 (78.36 lb-ft/L on the RLX), or BMW’s N53 (78.77 lb-ft/L on E90 330i etc.).
The 2UR engine was developed back in the early 2000s. Although it received some updates along the past 15 years, its main design and architecture are fundamentally unchanged (or else it will require a complete new design). From today’s standard, it is way outdated. For example, its direct injection portion of the fuel system is still the oldest 1st-gen wall-guided DI type (compared to most of the latest DI engines, which are already using spray-guided or air-guided type design). Its cylinder block uses open-deck design partially due to consideration in cost saving (open-deck block is much easier than the close-deck version to be manufactured), which is weak to endure stress and higher output.
The D4S injection system and the DOHC valvetrain, which requires 4 camshaft plus the variable timing/lifting mechanism, also adds considerable weight to the 2UR engine, which makes it to 520 lbs: almost reaching the level of the cast iron block 6.4L HEMI V8, but with 13 less hp and 80 lb-ft less torque than the HEMI engine. As a reference: the 6.4L HEMI V8 weights at 582 lbs; 5.7L HEMI weights at 591 lbs; Hurricane twin-turbo 3.0L V6 standard output weights merely 430 lbs and the high output version weights at 441 lbs.
A quick summary on the 2UR-GSE: it is too heavy, and only slightly better in terms of output than some engines that are used in common “mainstream” cars you can see everywhere on the street. So it has a large gap to be qualified as a high performance engine.
The engine’s VE and power ratio will not tell the whole story of a vehicle’s powertrain. It is the compound result of the engine plus the transmission that matters. Therefore in the next section I will review IS500’s transmission.
Part 2. The Transmission
IS500 uses Aisin’s AA80E 8-speed transmission. This is industry’s first 8AT and is the most technically outdated. Due to Aisin’s obsession in using the compound planetary gear sets (Ravigneaux gear set to be exact), the Aisin 8AT has two major inherit drawbacks from day one:
- At each gear, it requires 4 clutches/brakes (inside an AT, its shifting elements are typically implemented as either clutches or brakes) to be disengaged, which brings in tremendous drag effect (compared to the ZF 8AT, which only has 2 shift elements open in each gear), and therefore leads to much higher parasitic loss. For consumer, they will feel the vehicle’s actual acceleration performance does not match the engine’s rated hp and torque that the auto maker claims;
- Many of the frequently used skip-gear downshifts fall into the double clutch-to-clutch type scenario, this means the 8AT cannot fulfill that downshift in one action, and that downshift is actually composed of two distinct shifts behind the scene. For consumer, they will feel those downshifts are slow and sluggish.
For more in-depth analysis of the AA80E transmission please check out this article:
Aisin Longitudinal 8-Speed Transmission Analysis
What we have reviewed in the above is reflected in the IS500’s instrument test result. I would like to call out Car and Driver‘s (C&D) test is the best resource we as the consumer can get. Main reason is the data that C&D publishes has been adjusted for environmental factors, therefore different tests in different time periods and locations can be cross-compared. At the same time, the way how C&D measures acceleration has ruled out the impact of tire slippage, so if a vehicle is tested slower, than it means it is really due to its powertrain, not because of other alibi such as bad tires or inexperience driver etc.
In the following I will post a couple test results from C&D, for powertrain I recommend focusing on these numbers:
- 0-60, 0-100, 0-130 mph, and 1/4 mile time: these measure under the brake-torque acceleration technique, how fast the vehicle accelerates. Since this process involves consecutive gear up-shifts, it also indicates how efficient and how fast the transmission shift under the single clutch-to-clutch operation. These tests have subtracted the 1-ft roll out time so there is minimum tire slippage counted because the vehicle has been moving.
- 5-60 mph time: this measures how fast the vehicle can accelerate under our “daily” driving style – not using the brake-torque method to start. Typically 5-60 time will be slower than 0-60 because in the 5-60 test, the engine need to first build up rev speed, and then the torque converter will spin up and finally being able to lock up to transmit maximum torque; for turbocharged engine, the turbo also needs to spin up and then provide enough compressed air to boost the engine output – all of these take time so adds latency to the 5-60 acceleration. Same as 0-60, this test will also indicate the transmission’s capability in up-shifting.
- 30-50 mph, and 50-70 mph time: from my point of view these are in fact the most important numbers because this is the reason most consumers want a high output engine: they want to accelerate promptly in the traffic, or pass other vehicle with ease. One of our frequent frustrations in a vehicle is: when the driver wants to accelerate and press down the gas pedal, there is an excessive delay that the powertrain reacts, or it takes the transmission long time to be at the right gear to start to provide sufficient thrust. Now, the 30-50 and 50-70 are testing exactly these scenarios. These numbers test the how the transmission performs downshifts, and usually it is skip-gear downshift.
Now comes one shocking fact: the 2022 IS500, with 56 more hp and 24 more lb-ft of torque than the 2008 IS-F, is slower in every acceleration subject. Notice the IS500’s 30-50 and 50-70 result: they are very slow given the engine’s output, in fact nowadays many 300 hp-level V6 turbo cars can attain similar acceleration.
Some people may say that is because IS-F is 169 lbs lighter, but the below IS500 and RC-F comparison shows slightly weight difference does not matter: the RC-F is heavier than the IS500, with the same engine and transmission, the RC-F is instead considerably faster in every aspect:
Finally let’s take a look what the IS500’s actual acceleration performance are equivalent to: the older Mustang GT equipped with the prior Coyote V8 (the 435hp version), and with the 6-speed manual transmission.
Again, some people may argue that the Mustang is 187 lbs lighter. But as mentioned above, this still does not explain why armed with a more powerful engine and automatic transmission (which we assume should shift faster than human being), the IS500 is still slower.
With that being said, my conclusion on the IS500’s powertrain is: an average engine + outdated, subpar transmission = less power to accelerate and sluggish shifting behavior.
Appendix – raw data table for engine comparison (no need to read)
| Toyota 2UR-GSE | Toyota 2GR-FKS | VW VR6 (24 valves) | Ford Coyote gen.3 | BMW S54B32HP | Ferrari F136F | |
| Applications | RC-F, GS-F, LC500, IS500 | IS350, RC350, LS350 (China mkt) | Porsche Cayenne (2nd gen) | Mustang GT, Mach 1 | E46 M3 CSL | Ferrari 458 Speciale |
| Number of Cylinders | 8 | 6 | 6 | 8 | 6 | 8 |
| Displacement (cc) | 4,969 | 3,456 | 3,598 | 5,038 | 3,246 | 4,499 |
| Peak HP@RPM | 472 (471 in LC)@7,100 | 311@6,600 | 300@6,300 | 460 (Mach 1: 480)@7,500 | 355@7,900 | 597@9,000 |
| Peak Torque (lb-ft)@RPM | 395 (398 in LC)@4,800 | 280@4,800 | 295@3,000 | 420@4,600 | 273@4,900 | 398@6,000 |
| Power Ratio (hp/L) | 94.99 | 89.99 | 83.38 | 91.31 (Mach 1: 95.28) | 109.37 | 132.70 |
| Red Line (RPM) | 7,300 | 6,800 | 6,700 | 7,500 | 8,000 | 9,000 |
| VE (lb-ft/L) | 79.49 (80.10 in LC) | 81.02 | 81.99 | 83.37 | 84.10 | 88.46 |
