Would you eco-mod a Mazda MX-3 ?

[Cd]

Ever since the Mazda MX-3 first came out, I have admired the aerodynamic shape of the car. However, I never could understand why the car had such horrible gas mileage ( 22 city /29 hwy with a 4 cylinder ! )
Another thing that puzzles me is that the car had a .32 Cd which is worse than my '93 hatchback Civic at .31
I have no idea what could cause the car to have such an 'average' aerodynamics.
I find myself still admiring the car though.
The car appears to be very ideally streamlined when seen from all angles.

The area around the tail lights and bumper should have a sharp separation edge to it, but other than that, the car appears as though it should have a very good Cd.
The Civic hatch has a similar rounded edge around the taillights, yet is more aero despite having a much greater angle to it's roofline and minimal plan form taper. Any guesses as to why the MX-3 would have higher drag ?

Besides having a great shape, the car has a very small frontal area as well.

So have any of you guys ever thought of eco-modding one of these cars, or is it hopeless with the gas guzzler engine ?

( Just 'imagine' if a VW diesel were transplanted in this car and the car had some aero tweaking done to it. )

- My apologies to those of you with slow internet speeds, since this thread has lots of linked images. -

[RobertSmalls]

A small car with a badly-tuned (for FE) four cylinder getting 20-something mpg is not hard to imagine. But looking at the MX-3 in real life and in pictures, it looks like it should have a drag coefficient much lower than 0.32.

I'd like to tuft-test one. If flow remains attached across the back of the car, I'd buy one and promptly put the engine on eBay.

How does it compare to the streamlining template?

[Cd]

So you would replace the engine - but with what ?
An engine transplant into a non original car would cost thousands.
Much better and cheaper to just buy an Insight like you have.

[bestclimb]

These are marketed as a "sports" car. It may be a gear swap could improve things greatly. I have a feeling that as a sports car the MPG number is not as important and so did not play as close to the line as they could have with their mpg numbers. It would be interesting to let somone with some skills drive one and see how they did.

[user removed]

Welcome To MX-3.com - Your Complete Source On The Mazda MX-3

This may help. From a brief scan it looks like the 1.6 liter single cam engine has the best factory ratios between the 5th gear and differential ratios which look good. The others had ratios that would be worse.

regards
Mech

[user removed]

The best EPA highway rating (new) is 34 MPG for the 1.6 liter engine. It may be possible to swap out the tranny for one with a better 5th gear and differential ratios. Same trans and engines are used in other cars including the Ford escort so used parts should be plentiful. I always like that design and considered buying one when they were new.

My 08 Altima Coupe has a CD of .31 listed but it sure seems to coast better than the CD would indicate. I would bet the CD on that MX3 would be lower. Sometimes things like wings and bigger tires can make a significant difference. The Altima is listed as the same CD for a 4 cyl and 6 cyl so that doesn't seem to make sense because the wheels and tires on the 6 cyl are much wider.

regards
Mech

[RobertSmalls]

Is the coasting ability due to the mass of the Altima? Insights don't coast all that well because they don't have as much momentum as most cars at any given speed.

@Cd: A 30HP electric motor, with a clutched 1cyl diesel. But you're right, it's better to do that to an Insight. The money you'd save on batteries alone by choosing a better glider would pay for an Insight.

[user removed]

Robert, the Altima is no lightweight at over 3k pounds, so it has high sectional density (using a ballistic term). I did a coast down from 60 to 35 Mph and it took .6 mile.

Not to thread jack.

The MX3 might be a good choice if you have the talent to make some simple swaps. In particular the 85 HP 1600 engine and the highest overall ratio of top gear and diff, which works out to less than a 3 to 1 final drive ratio, which is excellent for lower revs at higher speeds. Could be a great combination.

I'll check it and edit this post to add the numbers.

edit:
not sure what car it is but there is a sedan listed on the site that has a 3.619 final drive compared to the coupe (car in discussion) that has a 4.105 final drive. Overall final drive would be 2.64 for the sedan and 3.00 for the standard trans in the coupe.5th gear is .731 overdrive in both, only difference is the final drive ratio.

If the tires were about the same diameter as a new Corolla at 840 revs per mile. That would be 2520 for the standard trans in the car, or 2217 (at 60 MPH for both) for the trans from the sedan. With the stock SOHC engine which is not high horsepower or performance that would be a sweet setup for mileage with the sedan transmission.

Ford models of the Escort, Merc Tracer, and even the Probe use common parts with the same era Mazda, so their are parts all over the place,

regardss
Mech

[Cd]

Mech, I love the design of your car. It is very similar to the G-35.
Sometimes I even get them confused from a distance.
I can't help but stare every time I see one.
About the Cd rating, when the second generation Eclipse came out, MotorWeek had an article on it that stated that the car had a .29 Cd " no matter how wide the tires are ."
I think we all know that to be ...um.... not so accurate.
Sometimes little 'misprints' get by unnoticed.
I don't doubt your car has a .31 Cd, in fact I'm surprised it is that high since the car looks so sleek.
Very nice design !

So now about the MX-3 - thanks for the link to mx-3.com. I have been there on several occasions.
I really wish I could buy one of these little cars and get the same mileage as a Civic.
The 4 cylinder car came with 88 HP, so it's not like they tried to make it a hot rod.

From the owners manual, the gearing on the '92 model is as follows
1st 3.42
2nd 1.84
3rd 1.29
4th 0.92
5th 0.73
Final 4.11

The auto had 2.80, 1.54, 1.00,0.70 ( 3.83 final )

The car weighed " 2,335 lbs " with a manual.

[user removed]

The sedan with the better differential is the 323. The Mx3 is the same platform as the 323 so parts are a dime a dozen. Also the same years Ford escort and Merc tracers.

cd, that Mx3 combo could be a real sleeper if you could find one dirt cheap that needed a tranny, you could grab out of a pick and pull.

Thanks for the compliment on the Altima. First time I saw one I did not even know they were making them. I rebuilt a bunch of them (Altima sedans) from model year 1993 (first Altima ex Stanza) to 1997. This one was loaded but a 4 cylinder CVT, had 7700 in options on it, and I fixed it for about $11.5k. Current cash value (not totalled) is about $19k.

If I get tired of it I guess I could just slam on the brakes and teach a tailgater a lesson in courtesy . Just kidding.

That little MX 3 would make a nice mileage car. I especially like the small grille openings and the overall shape of the car. If I was younger and could work on them without the old arthritis making it hard to get a good nights sleep I would consider one in a heartbeat. The design is totally current in my opinion.

The cheap stripper would be the best choice without all the powered crap that falls apart and cost a fortune to fix. Probably cheaper to buy. Bunch of them on our local craigs list.

regards
Mech