better daily driver? M20b27 or M40/M42

[2mAn]

Currently I daily drive an 86 eta and I love it. The good usable torque, the ability to merge and the sound are all big pluses in my book. I avg about 22-25mpg with a ~ 70/30 city/ hwy mix. Car is chipped, long tube headers, no cat, and 2.5" exhaust.

Im curious what the M40/M42 guys think of their cars as far as driveability, mpg and everything else. Do you feel like you need to rev it out to get to any usable power? I know the mpg is better, but is it a sacrifice over a torquey inline 6?

Any other options out there that you think is better?

[slammin.e28]

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.

[Kershaw]

i got 30mpg in my eta. your chip is probably killing your mpg.

[Wschnitz]

I can get 27 hwy, thats with a shot muffler and broken 02 sensor and probably other small things.

[2mAn]

i got 30mpg in my eta. your chip is probably killing your mpg.

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.

[Nick_S]

Love my M42 but if you want to get moving quick you do have to rev it out. Good mpg, been super reliable for me. It could use a bit more torque in the low end for sure.

[slammin.e28]

I got complimented by a fried who has a Euro 635Csi. I kept up with him in DC traffic while he was hardcore weaving and running.

Granted his M90 didn't have to work as hard as the M42 I was driving, but I kept the fuck up.

Point, the M42 is a fun little high revving engine. I like them for their modernality (word? Lulz).

[thatguyMatt]

M20 is a easier DD because of all the low end torque. M42 is more efficient but you have to work it harder to get power out of it. I prefer the torqey 6.

[Grant318is]

M42 is not a HP or torque monster, but I love my 318is. Its a fun, high revving engine in a light, well balanced car. I don't think the eta has that same feel. If you go from driving an inline six (in my case an e36 m3) you will feel like you are revving it out and killing your mileage, but you arent. After you realize that, you'll find yourself revving it out at every light.

[James Crivellone]

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

[Nairb]

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

Heresy and truth all at the same time.

[HarryPotter]

The b27 is indeed a really great DD motor. Plenty of tq. I dd'd two of them before I got my b25. IMO the b25 is more fun. luls.

[CrusherCurtis]

I voted e for reliability and torque.

[delatlanta1281]

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

This. M20's are reliable as hell. Especially an eta. Take care of an eta and it will last forever.

[glucklich21]

I drive my 318i 60 miles each day on the highway going back and forth from school usually at 80+. Sitting at almost 4k is kinda annoying particularly when you go up a hill at those revs and you still have to put your foot in it. Around town I love my zippy M42, but the highway is one I would leave for the eta. Also the M42 with AC and power steering on/connected, its painfully slow getting onto the highway, so much so I think its a tad bit dangerous with the AC on. This is a 100% stock M42.

TL;DR


M42 if you do a lot of city driving, eta if you do a lot of highway.