I have 1995 Lexus SC 400 and Lexus SC 430, both were doing 18 mpg, suddenly both dropped mpg sc 400 is 1995, 10 mpg and the other to 15 mpg. It is 2003. No spark plugs have been changed but the drop
I have 1995 SC400 and 2003 SC430 both were doing approximately 18 mpg.
Suddenly both dropped to 10 mpg and 14 mpg. Dealer cannot figure out.
HELP,