MPG Question

[neilnoff]

Currently have a 500 Cummins in our '08 American Eagle & it provides more than enough power. Considering (?) a newer model coach and some of the ones that are catching our eyes are powered by 600 HP Cummins. Wondering what type of MPG difference to expect? I don't we don't buy these rigs with MPG as the over-riding concern, but I get about 6 - 7 on the Eagle and would like to not drop way below that if possible. For the record, we are never overloaded and I drive like the grandpa I am - 65mph highway and I always get where I'm going (although usually not first!). Thanks in advance for any comments of real life experience with the higher HP coaches. Regards.

[Mentor]

Higher HP = higher fuel consumption, in this case 20% more but that said it boils down to driving habits on how much HP you use as that is the determining factor, in all probability if you drive the same you will have much the same HP requirements so little change, a tad more but not much.

.34 lbs per HP per hour fuel consumption.

[IASM]

We get around 6.5 to 6.8 loaded and towing. Speeds are around 65 to 70 depending on road.This is what is reported by silverleaf. I have never checked the mileage manually.
08 45ft ISX600

[Cat320]

Keep it at 60 and your MPG will improve.

[neilnoff]

Makes sense. I also found a thread from last year (should have looked for it first, I guess) with good info. Sounds like I should see pretty similar mileage as long as I drive the same way as I do now (speed, weight, etc.). I am no lead foot, just anted to make sure he me did not plummet. Thanks all for the responses & be safe --

[Cat320]

I haven't had mine long enough to get a good feel as to what will be my normal MPG. I've been told by owners with the same coach/eng combo between 8 and 6. The guy who said 6 cruises 70 to 75. The other guy said he does 60...which is what I did in my previous coach that had a 400 ISL and was 10k lighter. I'm thinking it will be somewhere in the middle, as 8 sounds high and 6 sounds low.