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One of the last models of the E30 range to be added was the 318iS - a 2 door saloon. The 318iS was fitted with the M42 engine, the most up-date-engine fitted to any E30. It came with Sports Suspension (including rear Anti Roll Bars - ARBS), sports seats front vented discs; rear solid discs, power steering, electric windows, electric mirrors, de-chromed trim, M-tech steering wheel, leather gear knob and gaiter, front and rear spoilers and BMW sport seats. The 318iS did NOT come with a limited slip differential as standard but was a small case differential with a 4.10 ratio. The base model cost aproximately £14,750 when it was new. It started out life to beat the sports models that Volkswagon and other leading car manufacturers were producing (such as the golf GTI. Bmw set out to produce a sports BMW which would match/ beat the performance of the likes of the GTI with a 1800cc BMW. At this moment in time, the only E30 BMW capable of out-performing the GTI was the 325i. The M42 16V DOHC engine was developed which produced 136BHP and was one of the most technologically advanced engine for its time and is also one of the most fuel economic E30's achieving around the 33MPG with mixed driving . There were rumours that the 318iS actually out-performed BMWs own 325i, so they restricted the power so the sales of the more expensive 325i wasn't effected. But still with 126BHP/tonne, it still gives the 323i a good run for its money. In total, 41,234 318iS's were made which means that out of the full 2.2 million E30's, 1.86% of them were 318iS's. In 2001 the DVLA only had 1687 318iS's registered in the UK, the number has since thought to of fallen to around 900 which is making the 318iS becoming more valuable and sought after.



Main article: M42

Designated the M42B18, the M42 engine was the most advanced engine fitted to the E30 during the car's production run, and would continue into the engine bay of its replacement, the E36. While only having four cylinders, its lightweight characteristics and free revving make it a highly desirable model, especially for those unable to afford the insurance and fuel bills of a 325i.

To keep your 318iS running smoothly, make sure you service it regularly

Fuel System

Injectors: Flowrate: 170 cc/min

Test pressure: 3 Bar/43psi

Coil resistance: (@20 deg C/68 deg F): 15-17.5 Ohms

Ejection angle: 30 deg


Motronic : Bosch DME 0-261-200-175 Software version 1.7 (US details)

Spark plugs : 16mm 3 electrode NGK BKR6EK or Bosch F7LDCR. The Champion RC8DMC can be used too. Note a 4 electrode platinum plug has

been approved for the M42 engine with max. 100,000 miles life, BMW part# 12 12 9 071 003, NGK BKR6EQUP or Bosch FGR7DQP.

Installation torque 27-33Nm/20-24ft-lbs

Plug gap : As specified above, they are unadjustable (pregapped) otherwise 0.027"

Idle Speed : 850rpm


Front suspension Rear suspension

The 318is chassis was changed from the 318i to be stiffer, lower and with a less roll. So, the chassis was adapted from the 325i Sport which fitted these criteria. This suspension set-up is to M-Tech specifications and is comprised of:

-15mm front springs, -17mm rear springs, appoximately the same ratings as the M3

Firmer Boge gas dampers (shocks)

Stiffer 20mm front anti-roll (sway) bar

A 14.5mm rear anti-roll bar was fitted, although many US models had just 12mm

Larger diameter 51mm front struts (and therefore dampers)

Techincal info

Front settings : Castor 8½º ± ½, Camber -2/3rdsº ± ½, Toe-in 0.028" ± 0.024, Steering axis inclination 13 5/6thsº ± ½

Rear settings : Camber -2º ± ½, Toe-in 0.080" ± 0.031

Tyres : 195/65/V14 205/55/V15

Wheels : 14"x6", 14"x6.5", 15"x7", 4x100 cts mm bolt holes, centre hubs are 57mm, wheel bore 57.1mm

Wheel offsets :

6" rim width: 35mm offset

6½" rim width: 30mm offset

7" rim width: 25mm offset


Front : ATE or Hoeflinger Ventilated disc, 10.24" diameter Rear : ATE or Hoeflinger Soild disc, 10.16" diameter Handbrake: Drum, integral with rear disc, manually adjusted internally at rear of lever. Shoes usually last the lifetime of the car. Calipers: ATE or Girling Master cylinder: ATE Recommended Fluid: DOT 4 - BMW recommend changing the fluid every 24 months. I would recommend changing it before and after a track session also.

Rear pads: I use Pagid 0307NA

Front pads: I use Pagid 5035NA

Minimum pad thickness = 2mm

I would recommend replacing discs after 2mm of wear has taken place - thats a lot of metal removed! At this point they are vulnerable to warping, cracking and fade. New pads will take longer to bed and in severe cases, can jam the pads onto the disc.

A balance valve is fitted to reduce the proportion of pressure given to the rear wheels as weight is tranferred forward to prevent them locking up under hard braking.

Some models (especially in the USA) had Bosch ABS. In the UK it was a £690 (1990) option.

Front discs are very prone to slight warping causing a steering wheel shimmy (a vibration) at around 60mph / 100 kph. If you seem to have trouble balancing wheels, then it may be indicative of disc condition.

Replacing discs is an easy job, takes less than one hour per pair and cost £50-£100 / $60-$120 for OEM discs. I don't believe cross-drilled discs are good value unless you auto-X, as they can reduce brake effort and efficiency in normal use. Slotted / grooved discs are a better bet for an upgrade, but the best money is spent on good pads and regular (at least every 2 years) DOT 4 fluid replacement.


Designation: Getrag 240/5 No automatic gearbox was offered. Gear Ratio's and Max Speeds: 1st: 3.73 - 28mph 2nd: 2.02 - 52mph 3rd: 1.32 - 80mph 4th: 1.00 - 106mph 5th: 0.81 - 127mph Reverse: 3.45 Final Drive: 4.1, pulling 20.7mph/1000rpm in 5th


For your engine, please see Basic M42 Servicing

Lubrication Engine : Fully or semi-synthetic, 15W-50 depending on environmental temperatures (although I would recommend a 5W40, 5W50 or 10W50 fully sythetic) - 4.5 litres, 5.26 qrts Engine oil filter : Hengst E88H D24, in bowl type Gearbox : 1.2 litres, 2.5 pts BMW Mobile traditions CD-Rom designates DEXRON II automatic transmission fluid Differential : Castrol SAF-X0 75W-90 or Castrol Synthrax or Hypoid 90 (for open diffs). Castrol SAF-XLS for Limited Slip Diffs. Also see Castrol's website.

Common Problems

Main article: Common M42 Problems page

As favoured as the M42 engine is, it's not perfect, and has its own quirks that show up regularly. Aside from the lumpy idle and fuel smell that can plague all E30s, the 318iS is especially prone to ticking and tapping noises, profile gasket failure and problems with the timing chain tensioner.

Common upgrades

Most people instantly buy an open cone induction kit for their car. however they are not good for the engine, as they tend to take in alot of hot air into the engine from inside the engine bay. The best air filters tend to be a performance panel filter (e.g. K +N panel filter) or a different form of enclosed air filter (e.g. BMC carbon fibre induction kit). Most people will say that the original BMW air filters are the best - and they are very good and normally better than the open cone filters.

Another upgrade is to buy a chip for the ECU. Installing a chip can induce the engine into producing up to 12 extra BHP. It is achieved by giving the car a different fuel pattern to run on (in simple terms) which increases the rev limiter, increase the low end torque and makes the car pull better over the full rev range.

A less common modification though is a supercharger conversion. Possibly the most famous supercharged 318iS on the E30 zone is Appletree's iS with Eaton m45 supercharger


I have made two quicktime videos showing the car acceleration, one showing the 0-60mph (~9.1 seconds) and 0-100mph (~26.2 seconds).

Here is a comparison to some 1990-1994 sports coupes (not bad for a generation removed and with just 1.8litres!) sourced from various magazines:

Performance stats chart

  • Figures for E30 taken with a crew of two and a full fuel tank.

Max BHP : 136bhp @ 6000rpm Max Torque : 127 ft-lbs @ 4600rpm BHP/Litre : 75.6 Official MPG (Urban) : 26.9 Official MPG @ 56mph : 47.9 Official MPG @ 75mph : 37.2 30 to 50 mph in 4th/5th : 8.5/12.8 secs 40 to 60 mph in 4th/5th : 9.2/13.2 secs 50 to 70 mph in 4th/5th : 9.6/13.4 secs 60 to 80 mph in 4th/5th : 9.0/14.6 secs 70 to 90 mph in 4th/5th : 9.7/17.3 secs

Available Body Colours (Paint Colour Codes)

Available Interior Trim Colours:

Useful websites


BP's E30 318iS website

The M42 engine club

318IS magazine spread

**Part numbers were correct at time of typing, some may have been superceeded my a newer part. You use this information at your own risk - contact your local dealer to double check quantities/part numbers**

General Info

Weight balance = 53% front / 47% rear

Unmanned weight = 1125kg / 2533 lbs

Power to weight ratio = 123.6 bhp/ton

Wheel base = 101.2"

Turning circle = 34.4 feet @ 4 turns lock to lock (p/s), 4.4 turns L2L (m/s)

Fuel tank capacity = 61.8 Litre / 13.6 Gals

Cd(A) factor (aerodynamic drag) = 0.35

Base price when new = std £14,750 (1990), $21,500 (1991)

Please also see the E30 318is Register