Thanks Jim.

I've heard a rumor that midgrade (89 octane) shell gas gives the best mileage. I have noticed a drop going from Shell to BP. I'll swing back to Shell after this tank to see what happens.

It's great that Lexus is letting folks get away from premium. MB has a long procedure for getting regular fuel out of the system when premium isn't available. Please.

I think the new Lexus hybrid is spec'ed for regular. Cool.

 

Fogcutter, I must have really been tired when I posted that I'd been using 87 octane. It's 89 (and I use Shell to) the mid grade. My Shell card rebates 5% when the bill comes so that's not too bad at all.

 

Fogcutter, Lexus also recommends Premium for the Rx450h

 

The factory rep told my dealership where we have
the three grades of 87, 89, and 93 that 89 was just fine. The book recommended 91 octane. But he said that the 93 was overkill and 89 was close enough for the difference in price. I actually think it runs better on it. Just repeating what the rep said.

 

I've been using 89 octane (10% ethanol) for months on our RX450h and it runs great. When I did some testing shortly after we got the car, I did not see any real appreciable difference in mileage between the 89 and 91 octane.

 

Thanks, I saw that, but the salesman and service manager told me regular was fine. Both BMW and MB reserve the right to deny warranty work if you burn regular.

An aside, I really considered buying a diesel. I watched the price for months and it hovered a bit more than regular but consistently under the price of premium. The day I went to haggle the RX diesel topped premium by a dime and has been higher ever since.

And the diesel gets 15% less mileage than the RX. Glad I didn't go for the diesel but talk about torque. Man. Quite a machine.

Oh, the HS250h is spec'ed for regular, a first for Lexus. The RX is officially still premium rated.

 

So far, with only 300 miles driven and using premium gas I average 28mpg.
I think that's not bad.