E30 325i and 325is VS E30 M3 As Street Cars

In previous articles, I brielfy mentioned my preference for the E30 325i and 325is cars instead of the legendary E30 M3 when it comes to street driving. This is not some blind devotion to the regular 3 series or believing that the E30 M3's giant killer status is overrated, but rather a logical analysis of purchase cost, ownership costs, insurance, maintenance, and overall value for money spent. The principle advtanges the E30 M3 has in *racing* environments are its 4 valve/cylinder high-revving inline 4, which is basically 2/3 of the block from the M1/M635/M5/M6 S88/S38 engine, its wider track, beefier suspension design, quicker steering rack, and aerodynamic bodywork. However, on the street, the streets where most folks use these cars, the advantages of the M3 are not as clear cut. The simple M20 2 valve/cylinder engine is better suited for cut-and-thrust commuting duty. Let me go as far as to say that the 1987-1991 325i and 325is manual transmission cars are not that far off the pace of the M3 in stock form! Exhibit A is the February 1988 issue of Road and Track magazine, which compared the M3 and 325is. The M3 edged out the 325is in the 0 to 60 test, doing it in 7.1 seconds vs 7.5 (some other magazines reported 7.4 for the 325i/is) for the 325. The M3 held a minor advantage through the quarter mile, running it in 15.4 seconds at 91 MPH vis 15.7 seconds at 89 mph for the 325is. Interesting right? Now consider the fact that the M3 already has a 4.10 limited slip differential vs the E30 325i's 3.73 diff, thus giving the M3 a gearing advantage! Put a 4.10 differential in a 325i or 325is, and it will instantly make it faster than a stock M3, top speed aside. Now, I do realize the M3 has a 24 hp advantage stock for stock, with 192 horsepower vs 168 hp. What people forget is that the power curve/delivery and gearing play a large role in how quickly a car can accelerate. The peak M3 engine has much smaller usable power range, whereas the fat curve of the M20 325i engine is much less spiky. The area under the power curve of the six-cylinder is greater than the area under the power curve of the four cylinder, for the total RPM range used in accelerating. That's why the 325is is faster when you give it the same gearing. A chipped 325i or 325is with a MAF conversion (which is the only way to make a cold air intake effective on these cars) will narrow the horsepower gap considerably. You'll be within 10 or so hp of matching the stock M3 in peak horsepower, and have all that nice low and mid range power. Upgrade to a 2.7 liter conversion from the 1988 only 528e or 325 base model, add a Schrick cam and Mass Air Flow meter and you will be able to put the hurt on even many modified E30 M3's. Remember, in the end the M3 is still a superior performance car, with better brake design, suspension geometry, weight balance, braking dynamics, handling, and oh so much cachet and panache. Take a look at the Grassroots Motorsports Magazine's E30 comparison from a few years ago. They pitted a 1991 318is, 1990 325is, and 1988 M3 against each other on the street, autocross course, and on the road course. The high revving M3 was untouchable over 5000 rpm, and all agreed its ultimate performance ceiling was much higher, but the real world of cops, traffic, traffic lights, and sane speeds makes the decision much tougher. The 325is feels faster on the street, and besides, you can always swap in a M50 engine for cheap money. Have you considered how expensive the M3;s S14 engine is to work on or rebuild??