IS 300 MPG (Is 24 highway really all you can get?)

In news: snipped-for-privacy@posting.google.com, Sapere Aude being of bellicose mind posted:

I'm driving a 2003 Corolla automatic. 65 mph is 2,500 rpm. You -can- overgear an engine to where OD gains you no more top speed than the next lower gear. THAT is truely an OD gear. I think the continual improvement in engine efficiencies (heat losses, VVT-i, stroke lengths, etc) are more responsible for MPG improvements than gearing.

Very true Philip (R) - If memory serves there have been Corvettes over the years whose fifth or sixth gear cut 25MPH+ from the top speed in the next lower gear.

Any IS 300 owners who know what mileage they experience out there?

The IS is not known for getting very good mileage, especially on the highway. It is mostly the "old tech" inline-six motor which has been around for a very long time. If you look at the specs, the GS300 with the same engine, also has relatively poor highway mileage, compared to more modern designs like the V6 Hondas. This is partly why this engine is doing away with the next iteration of the GS and IS.

If you get one, I would be prepared for 18-20 around town, 22-26 on the highway.

- Mark

Consumer Reports got 15 city and 28 highway. The highway number is probably optimistic as you can bet they were going the speed limit.

This is an ancient engine that had its glory years with twin turbos attached in the (sainted) Supra TT of the early to mid 90's.

Toyota ought to be ashamed of itself for continuing to sell this design in a premium priced sports sedan in this day and age and trying to market it as a competitor for the 3 liter six in the BMW 3-series.

GM gets pilloried for continuing to sell OHV engines like the Corvette V8 and the V6 in the new Malibu. At least those designs make state-of-art power and give excellent gas mileage for their output. The IS300 six does neither.

Shame on you, Toyota. Thankfully, relief is on the way in the (unfortunate) form of a V-6. Sure hope this is not just a rework of the Camry six. Wish they had stuck with an in-line six.

- GRL

"It's good to want things."

I have a 2002 IS300 with the 5-speed manual. The lowest around town mileage that I've seen in the year and 3 months I've owned it is 21 MPG. The best mileage I've seen was 27 MPG with mostly highway driving on that tank, some of it cruising at 75-80 MPH. Every day mixed driving nets 22 - 24 MPG.

I've just fitted a Borla cat-back exhaust and am tracking any effect on mileage. Borla tells me it should improve, particularly in highway driving.

I think the main reason the IS300 is not more economical is the short gearing. I'm turning 3,000 RPM in 5th at 70 -75 MPH. A 6th cog would really help I think. The engine may be Toyota old school, but it sure is a smooth sweetie to drive.

2003 Corolla / auto turns 3,100 at 80 mph. The 1ZZFE is an "under-square" engine (bore 79mm / 91mm). Is the stroke on the IS 300 less than 91mm?

No doubt about it, the IS is a gashog. Reasons I've heard range from the short gearing (the engine turns around 2750 at 60 mph) to the fact that the engine itself is an old design.

The best I've ever managed > Just curious as the larger Toyotas and Lexus with larger engines seem

RPM / gearing really should be reconsidered in terms of piston speed. Honda has built a reputation on short stroke (= low piston speed) engines that must be run at higher RPM to achieve piston speeds (air pumped) to equal that of longer stroke engines. That said, other inefficiencies probably exist that are more influential such as higher friction reciprocating parts.

I drive 64 miles round trip every day to work in my IS 300. In 10,000 miles, I have an average mpg of 23.54. I do tend to have a bit of a heavy foot.....

all i can say is I have had my IS since i got it new in 01 and its been a great car way better than that BMW 3 series i had, but i have never even though to check the gas mileage, thats not why one would buy a lexus, if you want mileage I suggest a toyota prius or something.

Mike

IS300 engine is old design: yes. IS300 gets miserable gas mileage: yes IS300 is fun to drive: yes IS300 is quiet: yes IS 300 is reliable as all hell: yes Knowing a good BMW mechanic: priceless

I turn 4,200 at 80 in an 01 Prelude -- 200 hp 2.2 ltr VTEC and get around

31-32. The Prelude will run rings around the IS 300 as well -- and cost far less to buy 2-3 years ago.

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