fuel economy at 70-75mph down i75?

Last week I've traveled along US Interstate 5, non-stop from the Mexican border (Tijuana, Mexico) to Los Angeles, CA. using the cruise control set at 70mph. I did an average of 48mpg, with outside temperature of about 61F to 63F., the distance is about 150 miles. My 2010 Prius was fully loaded with 4 adults & baggage.

Tire pressure was set at 42psi (front) & 40psi (rear), with Michelin Defender XT on all four tires.

 

50 MPG is a maybe if you pump your tires up as far as you can stand it. Suggest you drive 65MPH for safety.

I usually drive the back roads from my house as it is a 4 lane HWY and light traffic and 55MPH is easy to do.

 

You mean 70-75 MPH not MPG...Lol.

you'd def do a lot better set to 60 MPH for the entire trip.... I travelled half way across PA on a trip w/ cc set to 60 and yielded over 50 MPG w/ my persona which has the 17" wheels set to 44/42..

I chug along on the notoriously manic I95 at 55 MPH w/o issue on my commute.

I'd say if you cruise at 60 MPH heading south the whole way you'll be in the mid 50's for mpg, But remember if you are talking about leaving on your trip in the next few days It is currently the coldest week in the past quarter century in the mid Atlantic so take that into account and expect less MPG....