http://www.answerbag.com/profile/177942 New Answerbag answers from Davie Tue, 29 May 2012 14:29:11 -0700 Tue, 29 May 2012 14:29:11 -0700 http://www.answerbag.com/a_view/1148531 What is the average MPG for a semi tractor?<br /><br />a class 8 highway tractor will vary depending on it brand of engine. caterpillar averages 6.5 to 7.5 cummins averages 7 to 8 detroit averages 7 to 9 and mercedes benz engine averages 9 to 12. some of the mercedes engine have turbos the will spool up to 50 000 rpm. that amazing for a... Sun, 29 Jul 2007 11:27:12 -0700 http://www.answerbag.com/a_view/1148531