[MetroMPG]

I'd seen this article before. It contains some good info & and a lot of really misleading & confused info.

Comments...

• I'd forgotten that they actually quantified the vehicle weight when talking about the "carrying additional weight penalty". Even the oft quoted EPA stat doesn't put it in context
  

  "Add 100 lb. to a 3000-lb. package, and this 3-percent increase in load invokes at most a 1.5-percent penalty at the fuel pump."

• On the subject of WOT/short shifting, they are somewhat misleading.
  .
  • First off, full WOT will retard ignition timing and enrich the fuel mixture - there goes your efficiency gain from reduced throttle losses!
  • Second, if you use this accel technique, you must not brake after accelerating. The penalty of converting kinetic energy into heat & brake dust after a vigorous near-WOT/short shifting acceleration is massive compared to doing the same after a theoretically inefficient feather-footed acceleration.
  • Third, if your target speed is high and you'll be cruising at it for some time, it is not as efficient to near-WOT/short shift to get there. Try it, with instrumentation, and see.
  • Near WOT/short shifting to reach some target speed works best when it's done during P&G, or if EOC follows.

• It suggests shutting off the engine isn't worth it "Unless the stop is prolonged (a railway crossing, for instance)". Perhaps true in a large, old, cold, out of tune engine that doesn't start up easily, but we know it saves fuel in a small, warm, fuel injected engine that restarts well - even if the stop is very short.

• The article confuses coasting in gear for fuel-cut with coasting in neutral, no fuel cut.

• And it is flat out WRONG in this statement:

  "Plus, of course, hybrids should never be coasted. Out of gear, they're giving away all of their coast-down regen."

  Coasting to a stop is hugely more efficient than using any form of braking, including regen in a hybrid.

There are some nuggets in there, but generally, I'd say: reader beware!