better daily driver? M20b27 or M40/M42

[AutoXinE30]

is that city driving? i get about 30mpg on the highway if i stay under 80mph. the chip is an ebay special so i know its not the best one out there, but the power gained is worth it. i dont think i noticed a big drop in mpg with the chip, probably around a 10% drop.

Weak.

The last trip I took I set my 87 528e (209k miles) on 60mph cruise and got about 40mpg on the way out (300 miles one way) and about 38mpg on the way home.

I actually got back out of the car and tried to pump more gas into the tank as I couldn't believe going 105 miles on 2.8 gallons of gas (stopped to fill up before crossing the border to more expensive gas). All stock, OEM tire size, OEM rims.

[2mAn]

Weak.

The last trip I took I set my 87 528e (209k miles) on 60mph cruise and got about 40mpg on the way out (300 miles one way) and about 38mpg on the way home.

I actually got back out of the car and tried to pump more gas into the tank as I couldn't believe going 105 miles on 2.8 gallons of gas (stopped to fill up before crossing the border to more expensive gas). All stock, OEM tire size, OEM rims.

i get well above 30mpg if im going 60mph, but i enjoy driving and 60mph is pretty boring. mine has larger wheels and tires (overall height is about the same, but a wider footprint). ive also got a little more mileage than you (223k) and I know my motor is a little tired as it dyno'd 90whp bone stock which is about 15% down on bhp. torque was stock though. it still needs some loving and a valve adjustment is on the list of things to do.

good info in this thread

[stamar]

Dad has a vert in each flavor. 325 and 318 M42.

I feel I have to ring the M42 a bit to get it going. The 325 not so much. But the 318 averages about 30mpg, so he says. I drove it the other week and it seemed to struggle getting out of the hole, but I do love M42s, and have been DDing my M3 for the past few months. It was down, so I borrowed dad's 318, therefore my perception may be flawed a bit.

because there was never a 325e convertible you were comparing the 325i to the 318 i.

the e has different gearing also. the actual track times of the two models theyre asking about are close to identical...
The E has higher torque, lower hp and higher gears....

the 318 weighs less and has higher hp and top speed. Better gas mileage. odds are its a better daily driver because there's less front end weight. slower at the take off and um I think 4 mpg better.

the only 325 e convertible was the baur model. Which is possible but rare. Im not sure how many E baurs there are in the us but a handfull or maybe none.

[Massimo]

I can get 33mpg with only city driving in my M42, we don't have highways here lol.

As stated before If you do a lot of city driving then the M42 is the way to go. But if it is mostly highway then go the M20

[Ryann]

In my experience the m42 has nothing on the 2.7 mileage-wise. I consistently averaged 27 mpg at 70-75 mph highway with my '91 318i, now worse (25-26) with the 16v 'vert, perhaps the combined effect of the shorter 4.27 diff and inferior drag coefficient.

That being said I think the m42 '91 318i/s is THE e30 to daily. It's light and a blast to drive on the back roads. It has better bumpers/valances, better window regulators/motors, lacks a distributor and belt driven cam timing, has a modern and clean looking engine bay, and with minimal attention will last as long or longer than the 2.7.

[TimKninja]

Ive had both.

Its hard to say. I could never get my M20 to not run rich. But it NEVER failed on me. Over 300k miles and perfect compression. Soooo reliable. Also terribly noisy.

This M42...I dont know what to think about it yet. Ive just done the mess under the intake because every vacuum line was leaking. Its a buzzy little motor but i dont trust it as much as the m20. Ill see how I like it after I bleed my coolant . Im probably managing 26mpg according to the econogauge.

[F34R]

M42's are awful little motors, M20B27's are fantastic for daily drivers.

This^ the M42 is junk

I adore my b27 over the b25, granted I get left behind after 3rd gear :(

Side note: GPS avg'd me on the highway at 2.5 rpm in 5th between 30-32mpg(65mph or so) I dropped to 29-30 at 3k about 70ish.

[carloserna]

i have an m42 and its reliable as can be. very quick and nimble especially if its chipped you feel much lighter and save gas..i also have an m20b25 i love both cars. they all have cons and pros yea fuck it...atleast its an e30

[long tall eta]

never drove the 42 but love my eta. chipped with a 3.25 lsd. 30 mpg highway at 60 or 65, 26 mpg at 80, but drops to 23 in the city. 320,000 on the clock and still runs strong.

[theox69]

I vote for an M42 with a Mark D chip, instead of an m20b27.
Plus there's no timing belt, so there's at least one less thing to worry about.

[TimKninja]

I vote for an M42 with a Mark D chip, instead of an m20b27.
Plus there's no timing belt, so there's at least one less thing to worry about.

Yea but theres the Idler pulley, chain tensioner, and profile gasket to worry about. The M42 isn't as bulletproof as the M20

[F34R]

Yea but theres the Idler pulley, chain tensioner, and profile gasket to worry about. The M42 isn't as bulletproof as the M20

^

[slammin.e28]

because there was never a 325e convertible you were comparing the 325i to the 318 i.

the e has different gearing also. the actual track times of the two models theyre asking about are close to identical...
The E has higher torque, lower hp and higher gears....

the 318 weighs less and has higher hp and top speed. Better gas mileage. odds are its a better daily driver because there's less front end weight. slower at the take off and um I think 4 mpg better.

the only 325 e convertible was the baur model. Which is possible but rare. Im not sure how many E baurs there are in the us but a handfull or maybe none.

This is why I mainly commented on how the 318 performed.

M20 is M20 is M20. They're awful little motors. M30B35s are fantastic for daily drivers.

[Oly_Schmidt]

The ETA is a fantastic DD. I slipped a 3.25 LSD in my last one and it performed at least as good as a B25 and got better mileage.
Haven't driven an M42 - yet.

[2mAn]

I keep making excuses NOT to buy a 3.25, but after reading over and over how much of an improvement it is, I cant resist