Tips on Buying Cars: Lexus Rx350, fuel economy ratings, fueleconomy gov

Question
Hey Jeff,

We're planning on buying the 09' lexus rx350.  I know premium fuel is recommended but it can use regular too but the fuel efficiency will go down.

I was wondering if anyone knows the MPG on regular fuel and MPG on premium?

If the premium is more efficient, then it will only cost a negligible amount more, but if not then it wouldn't be worth it.

Thanks:)

Answer
Check out this website:

http://www.fueleconomy.gov/

The fuel economy ratings for all vehicles built since 1985 are listed here, along with info on "real-world" fuel economy numbers.  The site is a little cumbersome to work with, so you may have to really dig to find the data you're looking for.  But your last sentence says it all: if you've made up your mind that this is the vehicle you're going to buy, then it comes down to which fuel makes the most sense.  Frankly, I don't think there will be much difference in mileage, but if premium gives you 8% better mileage for 5% more in cost, then go with the premium.  If the numbers are reversed, then use regular.  The only way you'll know for sure, within your own personal driving habits, is to buy one and compare the two fuels on your own.  

And "personal driving habits" are critical; even if you find a Lexus website with forums where this topic is discussed, keep in mind that how and where you drive can make a big difference in the final numbers.  Someone might tell you they've achieved 15% better mileage with premium, as where you may see no difference at all.