cholmes1

Did some searching and found a few threads in the forum on MPG for the IS-F but none related to the aerodynamics. I am curious what some of you believe would be the result of the different MPG's experienced by the two cars? Obviously the engines are vastly different, but with the 8-speed trans and the low final gear I can't see why this car would not get into the low 30's on extended highway drives. Especially if you are turning 1500-2000 rpms at cruise?

In looking at both cars I wonder how much the front fascia has to do with the IS-F having lower returns? Anyone think that the larger bumper with much larger openings is a big reason for the difference? Anyone know the drag coefficient of both vehicles?

The reason for these questions is that the IS-F seems to have all of the parts and performance bits I wish I had on my IS350, so it is just easier to buy the IS-F. So a swap will hopefully be in my future. I can justify the higher octane fuels, but only if I can get north of 30mpg on my 200+ mile weekend drives. Tired of hearing my Dad and brother brag about there lame vettes getting 30+ on the highway and still beating me at the track.

Thanks

mugenh22a4

iTrader: (9)

Just look at the Cd (coefficient of drag) for the two cars....

.28 for the IS350 versus .30 for the ISF. My guess in the difference is that maybe the IS-F's bodywork creates a little more downforce; downforce comes at the expense of coefficient of drag.

MRxSLAYx

The IS 250/350 has a lower drag coefficient(.028 compared to .30 for the isf). I would say that it comes down to MPH in gear actually. Not sure about the is250/350, but the isf is at 78-80mph at 2000rpm in the final gear. Sustaining 2000rpm at 80mph is going to require more force that 60mph. I dont know the gearing for the is250/350, so this is just a quick theory.

archie

you can get 30+ mpg in the isf. I have done it many times on road trips to vegas (240miles), utah (265miles), and california central coast (250miles).

the best i ever averaged on a trip to vegas (238 miles one way) was right at 32mpg but it was the most boring drive ever. i usually average between 29 and 30 mpg on a trip to vegas, but that is with spirited driving in certain areas.

on a trip to central coast (250 miles one way) i average 30.6 mpg. pretty flat drive, but without some traffic I am sure the numbers would have been higher.

i would only use the stickered epa numbers as a reference, but you can easily get higher numbers, but beware you can easily get lower numbers too. goodluck, and if you are reall that worried about mpg, stick with an is250.

jkeifer3

Lame vettes? Why lame? They seem to do everything quite well.

mugenh22a4

iTrader: (9)

Everything except the rental-car interior. But yes, performance-wise, it does everything very well, especially for its price.

heyarms

iTrader: (5)

Agreed... I was days away from getting out of my leased IS250 and into a C6 and it fell through. The whole time i wasnt thrilled about the interior... But still love driving and looking at them!

But to be on-topic... I dont think a 2% difference in drag is what causes the F to guzzle more gas....

mugenh22a4

iTrader: (9)

^^ For me, I think it's simply because the F has a bigger engine. However, the 7% increase in drag does hurt the gas mileage a bit.

NYC ES3

iTrader: (7)

yeah everything except keep their detachable roofs secured to the vehicle while driving...LOL


Hands down bang for buck the Vette can not be topped or so was the case before the Nissan GTR
either way your Performace Toyota product will outlast them both with minor to no issues on the long run...all around better car

ToothDoc

7% difference in aero is about 2 mpg difference @30 mpg. I have seen as high as 30.2 mpg on my IS-F during highway cruises. Having said that, my F sees roughly 1-2 mpg worse than my IS-350 driven the same which is about right considering it weighs about 150 pounds more and is less aerodynamic.

cholmes1

This is great news! Thanks, ToothDoc I still need to meet up with you next time I am up that way...Want to see that homemade battery.

Also, the reason I said 'lame vette' is because they have been pressed upon me since I was a child as then end all be all in performance cars . Clearly they are a great value, but I prefer a little more exclusivity if I am going to shell out $50K+

Regardless, based on the given information and the other MPG thread with members hitting 26-28 with what I assume is traffic or aggressive driving, I think an IS-F could be on the horizon. Not many cars can provide the combination of performance, real-world practicality, and exclusivity that comes with an IS-F. Knowing my driving style I am sure I can hit 30mpg without too much issue Thanks again for the information.

avgj0F

iTrader: (2)

What a real fun with 30 mpg?

JMBillsta

iTrader: (6)

damn those are good numbers, wish i had your foot-control. if you looking for a fun drive, the zzyzx exit (15 mins past barstow) has a 4 min stretch of smooth pavement with mini hills and sharp turns. but go too far and youll get rocks and reach a mojave desert center.

melbitoast

iTrader: (1)

The best I ever hit in my IS250 was just over 34mpg on a 225-mile drive from Austin to the north side of Dallas. I have yet to be able to control myself in the ISF, so I'm not sure exactly how high it will go. I averaged about 28-29mpg on my way back from Dallas the day I bought the car b/c I managed to restrain myself for 95% of the trip.

Aerodynamically, the fascia could have something to do with it. Perhaps the raised hood may have the slightest effect. And I am assuming the ISF weighs considerably more than the 250/350, so initial acceleration could be a factor. --> just looked it up. IS250 is ~3450lbs, and the ISF is ~3780lbs. That's a 9.5% weight increase! That has to be a factor.

Lets Drive

iTrader: (3)

As others have stated, it's possible. I've managed a best of 31.5 one trip, all flat highway, w/ cruise control, and no traffic, though it was less than 200 miles. A bit more than 28 is normal, and pretty consistent for me, though.

I don't think fun has much to do with it, but saving fuel on long(ish) trips is a bonus.