I was reading through a thread on the Cruzetalk forum and someone linked to a Tire Rack test from 2009, comparing LRR tires on a fleet of Priuses. Here's the article:
Tire Test Results : When Round and Black Becomes Lean and Green
In this article, the following claim is made:
"The Prius hybrids used for this test returned an average of about 52 mpg... [show FE% improvement chart] ...you can also apply similar percentages of improvement in fuel economy to other vehicles. The fuel saving dollar value of eco-friendly, low rolling resistance tires essentially doubles or quadruples when applied to typical cars that deliver 25-30 mpg or light trucks and utility vehicles delivering 12-15 mpg."
Is it just me, or is this statement completely false? Im my mind, taking a theoretical car that weighs the same as the Prius, uses the same size tires and has the same suspension alignment, but gets 30 mpg on the highway instead of 50 would benefit proportionally LESS than the Prius, not proportionally MORE as the article states...
If the LRR tire upgrade on the 50 mpg Prius netted a 5% increase in FE (+2.5 mpg), then the same tire upgrade on the 30 mpg car would only see a 3% increase in FE (+0.9 mpg).
To be clear, since the cars would both lose the same amount of energy due to rolling resistance, both cars would save the same amount of fuel per mile driven with the LRR tire upgrade, but the
percentage of FE improvement would be less for the less efficient car since it uses more fuel to begin with. The Tire Rack article claims the opposite.
This is the way my mind approaches this... am I on the right track here, or am I out in left field? I wanted to put this in front of the "experts" before commenting on the other forum. Thanks!