Brendon

iTrader: (1)

I've been keeping up with the Lexus IS' changes for 2011. One thing that stands out is the jump in MPG rating. For the past few years since the new EPA standards went into effect, the IS350 has had a rating of 18/25 MPG. Now for 2011, the IS350's rating has jumped to 20/27 MPG for the RWD model. That's a pretty significant increase, especially under the new, tougher EPA testing methods. In fact, its starting to cut down the IS250's only real advantage (the 250 is still rated at 21/30 MPG).

Anyone know why? Its more just out of curiosity that I'm asking. As far as I can tell, there's no changes to the engine at all. I thought it might be that Lexus was giving the IS350 its little brother's lower 3.92 diff to improve MPG, but according to the Lexus website, its still using the same 4.09 from last year. Could Lexus be adopting the cylinder shut off system like what Honda's using?

Nigel-JDMParts

iTrader: (74)

My real world MPG for my IS350 is Avg 21 to 23MPG all day long.
I had done 29MPG with 85mph in a 100 miles trip.

lexusis305

iTrader: (2)

Its all in gearing and if you have a 250 or 350 stick or auto , also no changes to the motor is the same throw 2006-11 for 2gr & 4gr motors , but the honda thing is not set up to work with 1600psi fuel system lexus have is alot better then that of honda I tell you because am a sensor lexus tech. you want better gas control your foot and used high octane no cheap gas

sangomaru

Probably it would be more difficult to sell that new IS350 AWD with EPA est. fuel ratings below 18/25? So, the IS350 EPA est. fuel ratings go up a bit 20/27 and the new IS350 AWD gets the old numbers of 18/25.

Hoovey689

iTrader: (16)

Actually the 250 has gained an mpg in highway. It was 21/29. I've seen enough 250 window stickers

edgeucated

iTrader: (4)

im pretty sure its just marketing scenes, like how they underrate the horsepower of certain cars to better sell heavier, more expensive models.

ex. is350 rated at 306 hp when its really rated at 316 horses, or bimmers 335 rated at a modest rate so that the m3 looks better

Brendon

iTrader: (1)

I wasn't asking about real world MPG. I was just curious why the IS350 is getting a 2 MPG increase next year by the EPA.


I'm not sure where you two are getting your facts from. The MPG ratings are conducted by EPA officials, not by auto manufacturers. In fact, the new EPA ratings are calculated by using computer programs, so there's little margin for error in the test, short of Lexus bribing an EPA official.

The same is true of power ratings. All power ratings since 2006 have been conducted by SAE certified officials, not by the auto makers, to prevent fudging numbers like what was done in the past. The only reason for claims of "underrating" or "overrating" have to do with the discrepancy between crank ratings (what is advertised) and dyno ratings (what's actually hitting the wheels). SAE doesn't do dyno power ratings because too many variables go into the equation (gearing, tire/wheel weight, and even the dyno itself). That's why, for example, IS350's might dyno at a higher number than the GS350's. Even though they have the same engine and tranny, if the GS350 has a different differential, or heavier wheels, or even just a heavier, longer driveshaft, that can affect its rwhp and rwtq

Kurtz

iTrader: (1)

I'm not sure where you are getting your facts from because they're totally wrong.

http://www.fueleconomy.gov/feg/how_tested.shtml


So no, the EPA doesn't do all the testing. The MFG does.

And they physically test the vehicle to do it.


Actually you're not quite accurate here either

http://www.sae.org/certifiedpower/details.htm


These absolutely are dyno ratings. They use an engine dynamometer . I'm not sure how else you think they'd measure the power of the engine.

The automaker does the testing, though he must do so under very specific conditions, including have a "certified witness"

Those folks don't work for SAE, they're just certified by them. Here's an idea of what the certification entails-
http://www.sae.org/certifiedpower/witnesses.htm


Anyway, as others have observed, the real world mpg of the IS350 is more like 21-22 city and 27-29 highway...

My 08 (old EPA standard) was rated 21/28... which is almost exactly the real world mileage it actually gets... and much closer to the 2011 numbers too.


But I suspect simply switching the oil to 0W-20 when doing the EPA test would get them higher numbers under the "new" testing standard.

kennymacks

The reason why the 2011 IS 350 has better fuel economy is because Lexus added secondary port injectors to the engine. Now, the 3.5L has BOTH direct AND port injection. Port injection is more efficient during low load situations.

lobuxracer

iTrader: (2)

Where did you hear this? The 2GR-FSE has always had port and direct injectors. This is true since 2006.

http://www.sae.org/automag/techbrief...1-114-1-17.pdf

Where do people come up with these blatant deceptions?

syzygy

I disagree that superior gas mileage constitutes any sort of significant "advantage" for the IS250 over the IS350.

Well, to be fair, whether or not you think the IS250's gas mileage is a "significant" improvement over the IS350's gas mileage is purely a mater of definition. When I see typical IS250 and IS350 gas mileage ranges overlapping, I don't think it's justified to chalk up gas mileage as a "significant advantage" that the IS250 has over the IS350.

The only advantage the IS250 has over the IS350 is that it costs a little bit less and posts better slalom speeds when modified with F-sport parts (compared to an F-sport equipped IS350, of course)

Hoovey689

iTrader: (16)

Agreed. Honestly the way I've always viewed it, the 250 is more like a 4-cylinder variant of the IS but with 2 extra cylinders to keep things smooth. It's neither the fastest nor the slowest, but one can't argue that the IS250 lacks a smooth and refined powertrain. Compare that to say "cross town rival" Acura TSX with it's buzzy little 4-banger. Both are entry level luxury/sport models, but the IS clearly comes out ahead with a smoother, more refined, polished feel. With more torque and essentially the same mpg's as the TSX to boot!

syzygy

Yep, I agree.

Given that I own an IS350, I will admit that whenever I get into an IS250 loaner - even for "normal" driving (i.e. no WOT) I am always somewhat annoyed at the relative lack of power.

For example, if I'm in my IS350 cruising along at 60 MPH and the car in front of me gains some distance as it accelerates to 70 MPH, I usually just barely dip into the throttle, drop usually to 5th gear (from 6th), and the acceleration in 5th gear from 60 to 70 is more than enough in the IS350 to satisfy my needs for leisurely cruising.

With the IS250, however, doing so doesn't always work. I have to dip into the throttle much more (obviously) to achieve the same effect. One would think that by dipping into the throttle more and achieving the same acceleration, the problem would be solved, but for some reason it isn't (for me). For me, at least, there's certainly truth in the concept of wanting to have "power on tap" even if it's not actively being used.

That said, once you get up to speed, though, cruising along at 70 MPH - the experience in the IS250 is exactly the same as it is with my IS350. There is no denying that the IS250 offers arguably the smoothest ride of all entry level luxury sedans available.

Koz

I read somewhere Lexus/Toyota would be increasing gas mileage (10 to 15%) on many of the 2011 models.

Koz

quick123

iTrader: (2)

I think Kurtz is right on the money...Here at Toyota, they are posting all the 0w20 benefits all over the place, I would have to assume that this is the ONLY change made that would increase MPG ratings...