by capev86 » Thu Nov 24, 2011 4:16 am
well, my dad's 99 chevy suburban 1/2 ton 2wd w/ 3.42 gears and o/d "can" get 22mpg. that's about 900 miles on a 42 gallon tank if you want to push it. also, traffic and driver habits can have a HUGE impact on fuel economy. so many people buy big 4x4's for their commuter vehicle and vehicles in general get heavier and heavier with all the safety features, extra sound deadening and creature comforts consumers demand. that cancels out much of the efficiency of new engines and sophisticated electronic controls as the power to weight ratio doesn't improve. yes, carbs like the venerable GM (Rochester) Q-jet are very good at providing both economy and performance, but can not adjust on the fly to changes in fuel quality, workload/terrain, elevation, etc. our fuel injected cars adjust the ignition timing a little as rpm changes, but it is nothing compared to the variable valve timing on some of these new models that can fine tune at any given rpm. heck, we have 4 cylinder engines (even naturally aspirated units) that make the kind of power some v8's were making 20 years ago. a 2.5 n/a could easily make 200hp if it had 16 valves and sophisticated modern controls to allow for higher compression levels.