Like The Sopranos or that poo you've waited all day to evacuate, all good things come to an end. And sadly for us, the hot 'n steamy relationship with our project BMW 135i has also been terminated.
The car was loaned to us by BMW so we could report on its driving prowess and maybe make a few modifications along the way. And while having the car three months before it was released to the dealers made us look like the cool kids in town, it turned out to be a substantial obstacle when it came to tuning.
Our first problem was finding wheels, since most tuners assumed the E90 3-Series wheels would fit. However, a BMW engineer explained it was if the 135i body had been dropped over the 335i's mechanicals. As a result, it was like a hippo in spandex - everything was squeezed in tight. Therefore, the suspension and brakes were right out in the corners, with not much room for wheels. So the offsets were shallow and the tire sizes were skinny.
In the end, we went to The Wheel Supply in Walnut, CA. They worked with DCR Wheels to create a set of its Nürburgring three-piece wheels with the correct offset to fill our fenders. They had to try several rim sizes, but eventually got it about spot-on. The forged centers and chromed lips proved very resilient, as were the custom-painted centers DCR produced for us. The next problem was suspension...
Our first call was to Turner Motorsport to discover what H&R Springs had for the car. H&R is always among the first to bring new products to market and, as it happens, they had a Street coilover kit and some meaty sway bars to replace the stock twigs. We experienced a few problems with incorrect installation and the front springs being a little too low. However, the teething problems were resolved, longer springs added and all H&R's 135i coilovers now benefit from our findings, which is nice to know.
The real benefit of the Street coilovers was the incredible ride comfort. Passengers would look at the ride height and assume the worst, but were pleasantly surprised they didn't need back surgery after riding with us. We daily drove the car at this height and it rarely rubbed, never crashed into potholes and provided plenty of comfort with genuine high-g cornering ability. We should also acknowledge the flexible sidewalls of the Continental ContiSportContact3 tires fitted to the car that provided a supple ride and plenty of grip.
Getting the stance right was naturally our first priority. Afterwards, we browsed the BMW Performance catalog online (accessories.bmwusa.com) and came up with a list of parts to achieve an OEM+ look for the 135i. What's more, the genuine BMW accessories would provide the same quality of fit, finish and durability as OEM.
The only plastic parts we used were the front bumper and side skirts. These were direct replacements, even using the same fixings. Once painted, they have the perfect OEM+ feel, yet the vents in the skirts and the wider front intercooler duct give our BMW 135i more attitude. We scraped that poor front spoiler almost daily and it took the wear without complaint.
The remaining exterior additions were BMW Performance carbon fiber parts. Again, the quality was exquisite; better than most aftermarket parts we see - although the price reflected that...
The parts included replacement mirror housings and a rear diffuser. Both fitted with the stock clips. Then a carbon rear wing replaced the stock trunk lip. It's more aggressively styled but doesn't scream aftermarket.
The same quality applied to the carbon interior parts. These included door handle, dash and center console trim. And, aside from removing the console, fitting was straightforward.
Stepping it up a notch, we went for devices with a practical use. First was the BMW Performance steering wheel. It has the same thick rim as the stock part and retains the multi-function buttons, but it's finished in black leather and alcantara. At the top of the rim are two LED strips that operate as programmable shift lights. There's also a central display with a number of timers including lap time, quarter mile, etc.
It even had a g-meter that measured braking, acceleration and turning force. Then there was a water and oil temp readout, and since all the information was taken from the car's CAN-BUS system, you knew it was perfectly accurate.
The same alcantara was used on the new aluminum shift lever and boot. These were the visual parts of the BMW Performance short shift system that used a modified gear selector mechanism to hasten gear changes. Again, the quality was superb, and it wasn't so short you risked missing gears.
Not many people seem to realize the 135i has some of the biggest brakes ever fitted by BMW. The six-piston calipers are incredibly powerful, and while you can buy the complete set-up from BMW Performance for a 128i, we used the optional, stock-sized drilled rotors on our 135i. These are again OE quality and performed faultlessly, providing stronger stopping thanks to a combination of better pad bite and consistent cooling.
Perhaps the only BMW Performance part that failed to live up to expectations was the stainless steel exhaust. The manufacturer quoted a 10hp increase but we failed to see this. However, it again fitted perfectly, since it was basically a stock 135i exhaust modified for performance. More importantly, it sounded like the dogs of hell when you got on it. At wide-open throttle, the car barked and swiveled heads, yet it would return to a sophisticated deep, rich tone under normal driving, and never droned.
We know many readers were disappointed we left the engine software upgrade until last. People were hoping we'd go big-turbo and aim for 1000hp, but it was never that kind of project... the car was borrowed and limits were set. What's more, BMW had embedded code within the 135i's ECU that would detect torque spikes and invalidate the warranty - not something we wanted to do with a car that would return to BMW HQ.
We were waiting for somebody to crack the codes, and finally GIAC unlocked the secrets. In fact, we covered the dyno runs last month (et 2/10) and found 41whp.
If you own a 135i or 335i (or 535i, X5 or Z4 for that matter), we highly recommend the GIAC software. It perfectly matches the car's personality, offering mild manners off boost and a huge surge when the two turbos spool. It didn't even seem to increase fuel consumption, nor was it lumpy or hesitant. Where the 135i was fast before, it simply became even faster.
We'd previously measured a 135i 0-60mph time in 4.9sec. These cars are seriously quick. But the software made it supercar quick. Turn-the-car-around-and-drive-that-road-again fast. It was a blast.
As the final indignity, we returned the poor girl to stock before returning it to BMW. Just a few scars from a lowered ride height remaining as the indication of its former life. We're going to miss the 135i. We still feel it's one of the best performance bargains on the street, better than the R32, far superior to the Infinity G35 or Nissan 350Z and possibly even better than the 335i - although that can be argued either way...
The 135i gave us 20 months of trouble-free motoring. It averaged a slightly disappointing 17mpg in the city and about 27 on the freeway. But it had the ability to surprise you every time you got behind the wheel. It was a comfortable companion that was ready for a canyon-carve whenever the mood grabbed you, yet it was subtle enough to escape unwanted attention. And for that reason, we'd recommend the 135i to anybody with a few dollars stuffed in their pocket who's shopping for a new or used tuner car.
We must also thank all the companies who worked on the car for us, including Turner Motorsport, The Wheel Supply, evosport, BMS, GT Pro and South Bay BMW. Their expert knowledge and our carefully chosen parts meant we produced what we consider to be one of the best 135i packages we've seen to date. Although, we're still looking to find somebody with a feature-worthy example...
Tech Spec
2008 BMW 135i
Owner: eurotuner
Location: Los Angeles, CA
Occupation: loafers
Engine: 3.0 six cylinder 24v twin-turbo with GIAC software, BMW Performance stainless steel exhaust
Drivetrain: stock six-speed manual with BMW Performance short shift kit
Brakes: stock BMW/Brembo six-piston calipers, BMW Performance drilled rotors
Suspension: H&R Street coilovers, H&R sway bars, Turner Motorsport sway bar end-links
Wheels & Tires: 19x8" front, 19x9" rear DCR Nürburgring wheels, 3mm front spacers, 225/35 R19 Continental ContiSportContact3 tires
Exterior: BMW Performance front spoiler, side skirts, black kidney grilles, carbon fiber rear diffuser, trunk spoiler, mirror caps
Interior: BMW Performance carbon dash, door handle and console trim, BMW Performance electronic steering wheel plus short-shift knob and boot
Contact: DCR Wheels (dcrwheels.com), Continental Tires (conti-online.com), Turner Motorsport (turnermotorsport.com), H&R Springs (hrsprings.com), BMW Performance (accessories.bmwusa.com), GIAC (giacusa.com), The Wheel Supply (thewheelsupply.com), evosport evosport.com), GT Pro (gtpro.com), South Bay BMW (southbaybmw.com)
Project 135i coverage
If you're thinking about building a 135i and want to look back over the coverage we gave our 135i, here's a rundown of all the stories we ran. Most can also be found at eurotuner.com
et 6/08 - Introduction of 135i, H&R details, VW R32 comparison test
et 7/08 - First attempt to fit sway bars
et 8/08 - Wheel and tire installation, Bimmerfest debut
et 9/08 - Sway bar installation
et 10/08 - Our Cars: monthly update
et 11/08 - Audi S5 comparison, Our Cars: monthly update, portable nav
et 12/08 - Our Cars: monthly update, SoCal Euro show
et 1/09 - Our Cars: monthly update
et 4/09 - Our Cars: BMW Performance parts preview
et 6/09 - Exterior: BMW Performance body kit and carbon accessories fitting
et 7/09 - Interior: BMW Performance carbon trim and steering wheel fitting
et 8/09 - BMW Performance exhaust fitting and dyno
et 9/09 - Update: longer springs, stronger end-links, BMW Performance drilled rotors and cooling ducts
et 1/10 - Our Cars: tear down
et 2/10 - GIAC software dyno test
et 3/10 - Summary
