[bestclimb]

I won't tell you to buy one but I will lay out a couple reasons for it.

It may not save you more money than 2 extra gears, but unless you do the work your self(and value your time at close to $0), and have access to free/super cheap parts. The ROE for an ultra gauge is much quicker.

I Have no doubt that my new ultra gauge has saved me more than it cost. Went from upper 30s to low 40s on my escort. The pay off was less than 3 months.

Yes a 5 speed will improve things, but you will still be scratching your head as to what rpm you are running at and if it is at an efficient load.

Everything RPM, gear ratio, engine load and speed works out to = some instant MPG, those instant MPGs average into a tank mpg. a $61 bit of kit (ultragauge) will work that out for you on the fly. No matter what transmission you have it helps to have some feedback.

Add to that the likelihood (especially on a 16 year old car) that eventually you will get a CEL makes a compelling case for some sort of OBDII readout.

If you are dead set against some sort of read out then I can say that in general a the more ratios available the more likely the engine will be in a more efficient RPM/Load range and more likely the final ratio will get cruising RPM down.