We have '04 Tradition with ISL(370) Cummins, F/L chassis(chassis date July '03). We are about 3900 miles into our Alaska trip with an MPG average of 6.3. In the C/G I met a couple with an '05 Tradition, same engine but on a Spartan chassis. He "says" he averaged 8.5 on the trip up from California.Was there an engine mode after my chassis was built that would account for the difference in MPG? Should I contact Cummins to ask this question? At $1.42 liter in Canada it adds up.

Are both coaches the same size, are the pulling the same weighted toad, does he drive the same speed as you, did he go over the same highways as you????There are so many different aspects to getting good mpg.Ron

You didn't indicate the weight of your coach, but even if you're in the mid 30,000 range, 6.3 mpg is pretty poor. Most ISC/ISL Cummins owners get up into the 8 mpg range, or better. (The ISM and ISX engines are down in the range you're experiencing.)

You didn't indicate the weight of your coach, but even if you're in the mid 30,000 range, 6.3 mpg is pretty poor. Most ISC/ISL Cummins owners get up into the 8 mpg range, or better. (The ISM and ISX engines are down in the range you're experiencing.) Tire pressure, speed, weather and a multitude of other factors can influence mpg.

Check the gearing on each coaches rear axle, that could explain the mileage difference.

60 mph in a 40' with ISL = 8.5 mpg.........68-70 in the same coach on the same road = 7 mpg........Most 38'-40' have equal rear gearing, but if they don't, it takes a heck of a gear difference to make that big of a difference.....Your weight and driving habits are the main contributing factors.

2004 ISL | Good Sam Community

Fishinghat
Explorer II
Jun 03, 2013
You didn't indicate the weight of your coach, but even if you're in the mid 30,000 range, 6.3 mpg is pretty poor. Most ISC/ISL Cummins owners get up into the 8 mpg range, or better. (The ISM and ISX engines are down in the range you're experiencing.)

Tire pressure, speed, weather and a multitude of other factors can influence mpg.
Fishinghat
Explorer II
Jun 03, 2013
You didn't indicate the weight of your coach, but even if you're in the mid 30,000 range, 6.3 mpg is pretty poor. Most ISC/ISL Cummins owners get up into the 8 mpg range, or better. (The ISM and ISX engines are down in the range you're experiencing.)
lanerd
Explorer II
Jun 03, 2013
Are both coaches the same size, are the pulling the same weighted toad, does he drive the same speed as you, did he go over the same highways as you????

There are so many different aspects to getting good mpg.

Ron

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