That's a good increase. When you drive on a highway, What speed do you go? The slower you go within the posted speed limits, The higher the average:
http://ecomodder.com/forum/showthrea...you-15182.html
I did read you're more likely to be involved in an accident if you go slower, Though, But at the same time you're not as likely to die in an accident like that as compared to a head-on. (Though situations vary.) Whatever you do, Be vigilant.