Get a bigger tire and will take away from the 4.12 gear. Not much but some.

 

Yup, that's pretty much the reason for the RPM difference. Why they did it is because it's an I4 engine and not a V6 like your old Pontiac. Needs the higher gearing for better acceleration. Going up in tire size will help the high RPMs on the highway as well as highway fuel economy, however city driving performance will suffer somewhat.

 

Tire size won't help all that much. A 5% larger tire will only drop the RPM by the same amount. Fuel economy won't increase by that number though.

4.12 is a huge (numerically) final gear.

My old Suburban only had 3.42 and would spin at 2k at 60mph

My old 1971 Riviera has 2.93's and a three speed. I rarely see over 1,800 @60mph

I had a 1995 Riviera for awhile too. @60 mph it would only be spinning 1,500

Getting used to a I4 on the highway is hard. At the same time though it's happier at 3,500 than my other rides.

 

You're putting up V8 and V6 examples against an I4. Those bigger engines put out a lot more torque at lower RPMs then our 2.4L (165 ft. lbs @5,200 rpm). My Wife's 2004 GMC Sonoma also has 3.42:1 gearing, but has a 4.3L V6 (245 lb·ft (332 N·m) at 2,800 rpm).

Typical 350ci Chevy\Buick V8 = 260 lb-ft of torque @ 2800 rpm
1995 3.8L V6 = 230 lb·ft (312 N·m) @ 2000-2500 rpm

So when your max torque band is low in the RPM range, you can gear down knowing the engine has the grunt to overcome moving the vehicle. When the max torque band is higher in the RPM range, you have to raise the gearing or risk bogging the engine down.

Almost all I4 vehicles cruise around the 3000 rpm mark (+/- on either side)

Oh and as an aside, the FDII model uses 6:12:1 differential gearing. This is how it gains it's 19:1 crawl ratio when put in Low Off Road mode (Which is just locking the CVT in 1st gear). FDI models, when also put in 1st gear have a 14:1 crawl ratio.

 

I'm running a 28.5" tire now, and I was getting over 26 miles per (U.S.) gallon over the summer. Had been at about 24 in previous years, so it was a noticeable increase in economy.

 

Are you sure that's the actual gas mileage now? Have you accounted for the larger tires affect on the odometer?

 

Trail Rated Patriots have a gear ratio of 8.12:1 so... it sucks a bit. (On the highway)

 

Wow, and I was complaining about 4.12.

What RPM does the FDII do at 60-70mph or 100-120kph?

 

I know todde, just throwing out some other examples.

 

well, I assume he did, otherwise he would have a lower fuel economy than previously, all things being equal.

 

Often a larger tires weighs enough more to offset a good bit of the potential mpg gain....

 

Now I have a question. Looking simply at the numbers If all three were going the same speed on the highway the manual tranny would be spinning 24% faster than the FDI and the FDI would be spinning a whopping 32.6% faster than the FDI?

 

At 65 in my 5-speed FD1 it's turning about 2450 rpms or so in 5th gear. Maybe a bit less. If I wasn't lazy I could add that display to my Ultra-Gauge and be more precise, but....