So I 've spent the last few months testing the various modes of the RCF and recording their respective MPG results. For the record my car is complete stock, I live South Los Angeles County (near Long Beach), and work in East Los Angeles County (near Pomona).

the test:
56 mile round trip commute to work/home. 33 miles to work, 23 home.
I have to take my daughter to school in the morning, she attends a G.A.T.E. Academy School 10 miles southeast of our home and work is 23 miles northeast of our home, this makes the drive to work a bit different than the drive home, but it does help in making ideal conditions for a mixed high/city test.

To work: 10 miles highway >65mph, 16 miles surface street avg. 42 mph (35-45mph zones, 17 signals, avg. wait at signal 1:15, 7 miles back roads >55mph 6% uphill grade for 1.2 miles, 3% downhill grade for 3.5 miles, flat 2.3 miles.
Return home, 2.7 miles surface street to and from highway, average speed 24 mph 4 signals, 3 stop signs. avg. wait 0:52, 20.3 miles highway, avg. speed in rush hour 38mph.

each mode was run for 1 month (20 work days) the car was not used for any other purpose but back and forth to work. That mode was used exclusively for the entire duration of the test. The calculations were made manually by figuring the total miles / total fuel. for that given cycle, the on board MPG computer was also reset for each test and matched my manual calculations with a very small margin of error. Each fill was approx. 14.5 gallons of fuel, vehicle usually filled within a 1-2 miles of the low fuel light activating.

ECO mode Avg. MPG
Vehicle Computer reports 24.2
Manual Calculation reports. 23.9
Avg. miles on 14.5 gallons 345 - 350
3 fill ups.

Normal mode Avg. MPG
Vehicle Computer reports 20.4
Manual Calculation reports. 19.9
Avg. miles on 14.5 gallons 280 - 290
4 fill ups

Sport mode Avg. MPG
Vehicle Computer reports 18.4
Manual Calculation reports. 17.9
Avg. miles on 14.5 gallons 250 - 260
4 fill ups

Sport+ mode Avg. MPG
Vehicle Computer reports 16.1
Manual Calculation reports. 15.8
Avg. miles on 14.5 gallons 220 - 230
5 fill ups


There is an 8 mpg drop between ECO and Sport+ mode.

in ECO the car shoves itself into 8th gear as quickly as possible and holds that gear as long as possible, I watched it hang in 8th coasting from 65mph down to 37mph, additionally it keeps the car in Atkinson cycle as long as possible, basically anytime the car is not under load. in Sport+ it holds each gear at higher RPMs for longer, and I only saw it go past 6th gear once with I was cruising above 90mph.

I also found it interesting that the on board computer seems to report 1/2 mpg more than manual calculations consistently.

While most people don't care because really who buys a car like the RCF for mpg? the fact is that for daily commuting, there is a 100 mile per tank difference between ECO and Sport+ which for me is 2 more round trips to work, or 2 more days between fills, also consider the difference of 2 additional fill ups riding around in sport plus mode over the same time frame, that's an additional $90-$100 in fuel that month.

Your results may vary based on the fuel and terrain where you live, CA fuel is crap, and the roads are as well.

 

I average 18.8mpg in Sport mode which is what I drive it in 90% of the time. Pretty consistent with your calculations.

 

Thanks for taking the time to do this testing. What brand of fuel do you use? I use Shell Nitro and seem to get better mpg on road trips but again this is very elevation change dependent so one can not really compare to your results.

 

Chevron 91 octane.

yeah as I said your results may vary.. I am planning a cross country drive in August. From CA to GA, with stops in AZ, CO, TX, TN, and GA. will be going the northern route taking US-40 from CA to CO then onto TN, and returning via the southern route US 287/US81/I-40. nearly 5,000 miles round trip over 3 weeks, It will be interesting to see how I fair overall. I'm hoping to see ~26-28mpg

 

Thanks for the report!
I know MPGs is the last thing on one's mind with this car but I must point out how good it is for all the power (and weight).

In comparison, my IS250 AWD at less than half the power and 300lb weight advantage is a "pig" at about just 2-3 MPGs better in the city and same on the highway!

 

I do a lot of highway miles and typically the car is in normal, never in eco and I have an overall average of 21 mpg at this point. It still gets a good dose of sport + but I do not hammer it from every start. I am at 6500 miles at this point with ~80% of it highway

 

Thank you for the numbers! Very interesting.

When I first got the car, I couldn't average more than 17 mpg (still hard now with all the WOT and sport + driving I do) haha.

 

yes mine is more mixed driving, I also suspect you have 93 octane in MO and better fuel than the crap in CA. as I said I am doing a 5,000 mile round trip cross country drive in Aug, it will be interesting to see how well it does.

 

thank you for the research!

 

Yes sir, we do have 93 it is all I use in the car

 

best we get here is 91 and it does make a difference.

in 2008 I did this same cross country drive in a Chrysler 300c, from CA to CO I got 23mpg in that from CO on using 93 I got 28mpg

 

You can thank CARB for the all crap they require to be added to the gas. We suffer in NV because of the crappy CA gas too since they must ruin it at the ports before it even enters the state.

 

I'll ask the logical question here. You bought a high compression, 5.0L V8, making 460hp....why in god's name are you testing mpg?

Come on....enjoy the car in the right way

 

Of course I bought the RCF not caring about the MPG but it is good to know, though, in case I do need to try to save some more fuel. Thanks

 

Guessing you scanned over the post and didn't read it fully, I already explained it in the original post.

I actually quite enjoy my high compression, 5.0L V8, making 460hp, I have 7 miles of my daily commute that is a back road that has 2 lights within that 7 miles (basically the turn onto the road and the turn off the road at the end), no cross traffic and is mostly twisties through a canyon area, the posted speed on the road is 55mph, but since I am typically the only one on it I carve it at 85-90 every day.

I drive it how I drive it, the test was simply to find out the real world expectations of the car. I like doing stuff like this, and have done so with my last 4 vehicles. I find it interesting that I can see real world results of 100+ more miles out a tank of fuel on a high compression 460hp v8 simply by turning a dial on my console.