John McGaw wrote:
> I suspect that no reasonable person would consider a new MX-5 to be an
> economy car or give the fuel economy a huge role in the decision to buy
> one but I thought that this might be of interest. Immediately after
> getting my "break in" miles put in on my '06 Sport with handling option
> done I drove up to Pennsylvania to visit my mother over Easter. The
> mileage between here and there is virtually all interstate -- just short
> of 500 FWIW.
>
> I knew what sort of economy my '91 Miata had consistently achieved on
> the same trip and expected the new one to get just a bit worse or, with
> luck, to achieve the same. Here is what happened on four fillups that
> were on the interstate mostly at 70-75 under cruise control: 32.0, 33.9,
> 35.1, and 32.7 MPG. I was truly shocked by those results but calculation
> of the overall consumption since delivery, including 1,800 miles of
> city, suburban, and interstate driving shows that it has been getting
> 30.7 MPG. I realize that the four interstate legs might be skewed by the
> imprecision of how consistently I was able to fill the tank each time
> but the overall figure should be relatively accurate.
>
> BTW: the interstate miles were done with 30psi in the Michelin tires
> rather than the recommended 29psi but I don't know how much that might
> have affected the economy.

That sounds about average for a Mk1 1.8 in the same circumstances. I
got 34mpg over the winter here in the UK, which is about the same
allowing for our larger gallons. I'd expect it to improve by 2mpg or so
in summer as the warm-up period is shorter and the fuel blend is different.

MX-5s/Miatas have never been economical cars given their small size and
weight. The engine is highly tuned (and runs quite rich at over
4000rpm) and the Cd is poor.