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Hi, I have an older GS300 which runs great but feels a bit clunky against a much newer IS350 FSport.
Just wondering - did you test drive a 3rd generation IS350 F-Sport VS GS350 F-Sport (or 4th gen) ~ what are your thoughts around Agility, Handling, Performance, and FUN? NOT more so luxury features per se (coz everyone already knows about this
I think that the engines on both these cars are quite similar so I guess it's pretty obvious that the 300+ lbs weight difference plays a huge role on agility, handling, and performance.
The GS (3726 lbs) is only 133 lbs more than the IS (3593 lbs). I found that they handle remarkably similar.
holy ****. didn't realize IS is such a heavy car.
I didn't test drive the GS. I just knew what a great car it was and waited till i found the right one. Bought it blindly 240 miles away, i am just that confident in the GS.
I drove both the IS and the GS, but neither were F Sport. I really can't remark for the handling comparison but the IS really handled well in my limited experience of a 10 mile drive. However, the interior space and the the seat width especially seemed too confined in the IS, so it really wasn't given fair consideration. But, if I were 30 years younger......
I drove both and the differences in performance like JDR76 stated are minimal. The GS really moves well for a big girl and you can't really tell it's a massive car until you try to park it or drive through a small opening in traffic.
Just like everyone else has stated, it is gonna boil down to how much space you need. I am 6'2 225 and feel much more at home in the GS. That and I won't want to smash my knees moving up the seats for child carseats in a few years when we decide to have kids.
My boss prefers the smaller size and feel of the IS350 and just picked one up this past weekend. The new generation IS350's are gorgeous, especially in white.
I drove both and the differences in performance like JDR76 stated are minimal. The GS really moves well for a big girl and you can't really tell it's a massive car until you try to park it or drive through a small opening in traffic.
Just like everyone else has stated, it is gonna boil down to how much space you need. I am 6'2 225 and feel much more at home in the GS. That and I won't want to smash my knees moving up the seats for child carseats in a few years when we decide to have kids.
My boss prefers the smaller size and feel of the IS350 and just picked one up this past weekend. The new generation IS350's are gorgeous, especially in white.
Your boss drives an IS, and you drive a GS...
Back to OP's question though:
Test drive - yes, IS slightly more nimble due to overall smaller package. The extra luxuries/touch&feel more than make up for that. For sure I had a bigger smile getting out of the GS than the IS.
Test ride (in the back seat) - had to saw off legs to fit with driver's seat in my driving position(and I'm only 6'). Immediate deal breaker. Even a Honda Civic or Corolla has more space in the back.
i cant stand the interior of the current IS, too small and the center console is too in my face. im 6'1 230lbs. I need my leg room and elbow space. the GS is beautifully perfect for me. and the GS looks alot better.
I had my 2006 IS350 for 178K and have about 3k on my new to me 2014 GS F Sport. I find the handling pretty similar and I appreciate the bigger size a lot.
The 3IS F Sport shares platforms with the 4GS, such that the 3IS is similar in weight and therefore quite a heavy car and only a little lighter than the 4GS.
However, "polar moment of inertia" determines the agility of the vehicle.
In other words, if two cars are the same weight, the car that has its mass more concentrated towards the center has a lower polar moment of inertia, and has more agility.
Thus, in this situation, the IS350 F Sport and the GS350 F Sport are similar weight, however the IS has its mass concentrated towards the center, and hence has a much lower polar moment of inertia - thus when you test drive IS350 F Sport and GS350 F Sport back to back, you will find that the IS is much more agile to changes in direction.
The difference is marked.
Because the IS is lighter, it also has more terminal grip.
At the limit of its adhesion, the IS will lose grip much more progressively and more controllably than the GS.
Thus, the IS is the driver's choice.
While our 3GS had a much better ride than our 2IS, our 3 & 3.5IS's have a much more compliant ride than our 4GS.
There is a theory that went around saying that the 4GS can afford to be firm, because people who want soft go for 6ES.
If the 3IS350 is quicker than the 4GS350 in a straight line, then it is only ever so slight, due to the little difference in weight.
Our 4GS is good, but in other ways.
Eg the GS has much better quality leather and stitching.
Our GS cruises much more quietly than our IS.
Our GS is much more spacious than our IS.
It is a slightly different story with our 2IS vs 3GS.
The 2IS was softly sprung, but very firmly damped.
The 3GS was very softly sprung, and very softly damped.
In the end, the 2IS is much more agile, with more terminal grip, but when the 2IS lost traction, it did so very suddenly and uncontrollably; because the damping control was excessive, the 2IS had a tiring ride.
Meanwhile the 3GS has a beautiful ride, but it's steering response was sluggish due to the very soft coils, hence the weight transfer to the outside wheels.
Terminal grip on the 3GS is not as good as 2IS, but terminal grip is decent, but the beauty of 3GS chassis is that loss of grip at the limit was progressive and controllable.
Both 2IS and 3GS suffered from 1st generation electric power steering which was not very communicative.
Below is a sports car and a sedan of the same mass/weight.
Because the sports car is shorter and narrower with its mass concentrated towards the center, it has a lower polar moment of inertia, hence greater agility - it increases the speed of change in direction compared to the sedan on the right.
Think of it another way.
Remember how an ice skater does a spin?
To start their spin, they wrap their arms around their chest to keep their mass concentrated towards the center like an IS.
Once the ice skater spreads their arms and legs out, the spin slows down.
The 3IS F Sport shares platforms with the 4GS, such that the 3IS is similar in weight and therefore quite a heavy car and only a little lighter than the 4GS.
However, "polar moment of inertia" determines the agility of the vehicle.
In other words, if two cars are the same weight, the car that has its mass more concentrated towards the center has a lower polar moment of inertia, and has more agility.
Doesn't that argument favor the 4GS as it's a tad bit longer than the 3IS and will have a heavier (read: more richly appointed) passenger compartment which will help centralize the mass of the vehicle better?
Lexus corporate shows a better weight distribution on the 4GS than the 3IS ... 53/47 vs 54/46. You'd also be hard pressed to convince me that the engine is mounted lower in the IS than the GS, and given its the same engine and transmission, there's probably a negligible amount of difference in the weight of the combo between the two.
Between the two the only difference I see is the absolute difference in mass and more importantly the shorter wheelbase of the 3IS which probably is what you're feeling wrt nimbleness/turnin. A 2 in difference on wheelbase is significant.
I'd also wager that the front lower control arm compliance bushing is stiffer on the 3IS than the 4GS which also contributes to a quicker change in direction as the force of the direction change is more directly transmitted to the tires and not first absorbed by the bushing.
Doesn't that argument favor the 4GS as it's a tad bit longer than the 3IS and will have a heavier (read: more richly appointed) passenger compartment which will help centralize the mass of the vehicle better?
Lexus corporate shows a better weight distribution on the 4GS than the 3IS ... 53/47 vs 54/46. You'd also be hard pressed to convince me that the engine is mounted lower in the IS than the GS, and given its the same engine and transmission, there's probably a negligible amount of difference in the weight of the combo between the two.
Between the two the only difference I see is the absolute difference in mass and more importantly the shorter wheelbase of the 3IS which probably is what you're feeling wrt nimbleness/turnin. A 2 in difference on wheelbase is significant.
I'd also wager that the front lower control arm compliance bushing is stiffer on the 3IS than the 4GS which also contributes to a quicker change in direction as the force of the direction change is more directly transmitted to the tires and not first absorbed by the bushing.
The longer and wider the vehicle, the further its average mass is distanced away from the Center of Gravity - which is the Yaw Axis.
With a longer wheelbase and a longer cabin, the 4GS's very heavy engine and fuel tank will be further away from the C/G Yaw Axis.
Because the cabin is mostly hollow, it does not have much mass compared to the engine, and fuel tank.
It is the engine/gearbox and fuel tank which are the two heaviest components from the Yaw Center.
That's why the sedan below has 3,324k lbs in sq polar moment, versus the sports coupe's 984k lbs in sq; there is a big difference in polar moment of inertia between the two.
Notice below how the sports car's engine and transmission centre of gravity are both very close to the center of gravity of the car?
Meanwhile the sedan's engine and transmission C/G is far away from its overall C/G?
The greater the polar moment of inertia, the greater the resistance to changes in direction.
Conversely the greater the polar moment of inertia, the greater the straight line stability for the GS.
I also forgot to mention that once a vehicle fish tails or even spins, the greater the polar moment of inertia, the harder it is to stop fish tailing and stop spinning.
Thus, small cars like sports cars, Mazda MX-5's and go-karts enjoy an agility advantage over their bigger brethrens.
Where the bigger sports cars like Lamborghinis and F1 racing cars come into play is with their linear acceleration, and height to width ratios.
Because they are the similar height but much wider in track, their lower profile is able to resist roll more, and hence resist weight transfer to the outside wheels, to grip on all four wheels evenly as much as possible - to pull more g's on a skidpan.
So, when test driving an MX-5 vs a Lamborghini, or a go kart vs an F1 car, the smaller cars will be more agile, ie faster changes in direction.
However, the big Lamborghinis and F1 racing cars will pull more g's on a bend.
Should the big Lamborghinis and Formula 1 racing cars fish tail or spin, it will be harder to stop the bigger cars from fish tailing or spinning, compared to stopping an MX-5 or go kart.
Because they have a lower height to length ratio, the bigger sports and racing cars will tend to have greater resistance to squatting and nose dive in the longitudinal dimension.
Weight vs Weight Distribution
The actual weight on each wheel determines the terminal grip on each tire.
A slightly nose heavier weight distribution will mean that it will break its front end grip, before breaking the rear end grip - compared to a vehicle of identical mass.
Losing front end grip is safer than losing rear end grip, but an experienced driver can deliberately take advantage of oversteer to throttle steer the car, with less busy work on the steering wheel.
Height & Center of Gravity
Yes, the 3IS is noticeably lower stance manifested by: a lower roof line, lower waist line, lower seating position, lowered suspension with less suspension travel, and hence lower ground clearance with a lower center of gravity than the taller 4GS.
That explains why my wife's 3IS is able to roll less than my 4GS, despite the fact that my 4GS has stiffer and less compliant coil springs for greater roll stiffness.
Suspension Bushing Stiffness
I have no idea how stiff the IS and GS's suspension bushings are.
However generally speaking, there are something like 3 major types of bushings.
1) Rubber, which is normally OEM, softest and least durable.
2) Aftermarket intermediate.
3) Aftermarket polyurethane - these are both very stiff and very durable, but the ride is very stiff, and usually only enthusiasts can tolerate the ride to obtain the extra edge in handling.
Having said that, I wouldn't be surprized if the IS and GS shared identical part numbers for the suspension bushings? One could always do some research and actually find out here.
However, the GS probably has a different suspension subframe, if not different fluid filled hydraulic suspension subframe mounts, because despite using firmer coils, the 4GS has a degree of physical isolation from vibrations not found in the 3IS, and the LS is said to be on another level again.
Conclusions
I'm not a mechanical engineer, but the most important fact for the OP is that the 3IS is noticeably more agile, and more dynamic than the 4GS.
For handling and dynamics - go 3IS.
Meanwhile 4GS has significantly more space, better leather/plastic quality & stitching, significantly quieter, with less vibrations, and more equipment.
Hard Pressed
If you ask me what is hard pressed to convince me?
It would have to be the linear acceleration.
Despite 3IS being a little lighter, I cannot tell the difference in linear acceleration.
Even if I used my stopwatch, human error and reaction time in pressing the start/stop button would be greater than the difference in linear acceleration between the two cars.
We'd have to use Correvit telemetric instruments to measure linear acceleration accurately.
However, 3IS & 4GS handling/ride & NVH can be easily felt through the seat of the pants - such is their difference in magnitude...
_
Outside of the great post by fellow member peteharvey, i've owned both a 2IS and a 4GS. The 2IS felt much more nimble, quicker off the line and more agile. Both of my cars were/are NON-F Sport variants...the IS had 17" wheels, my current GS has 18" wheels. The cabin of the IS felt a little more jarring and allowed more road feel (probably also due to the standard Dunlop SP Sport tires). The GS handles very well for its size and feels smaller than it actually is...but in my experience, the IS in its natural state (non-F Sport) is a drivers car even without all the upgraded wheels/tires/sport modes. The GS starts to feel like a real drivers car in the F-Sport version...i never drove a RWD 4GS, but I imagine even moreso the 4GS feels like a drivers car in the RWD F-Sport variant.
07-02-17, 09:50 PM
Did You Test Drive IS350 FSport VS GS350 FSport?
