1995 Dinan/BMW 540i

Last updated: August 21, 2024

1995 Dinan/BMW 540i (owned 1995-2000)
The original 'Spratt' batmobile

Now this car was one 'bad ass' sleeper sedan (especially for its day) - built in honour of the early AMG Hammer sedans - with its 438hp supercharged engine and 190mph top speed. It sat low to the ground, but otherwise the only clue that something was lurking under the sheep skin was a deep exhaust note. In an all-out drag race to Whistler one day this car pulled away from a 993 Porsche 911 twin turbo (404hp) during a hill climb from 160-300kph. This thing owned the road.

I had read all about Steve Dinan's obsession with modifying BMWs and called him up and asked if he could build me something special. He agreed to work with Weissach (our local Lotus and Lambo dealer) to provide all of the parts necessary (springs, shocks, bushings, sway bars, brakes, super-charger, injectors, new computer, wiring, limited slip diff, exhaust system, and even a set of 4 custom machined cam-shafts) - and after 6 months of wrenching and many $ in modifications, the brand-new 540i that I handed to them rolled back out into my hands a completely transformed car.

This was a car that a lot of people really identified with - including the local BMW service manager who would personally pick up my car for service and return it at the end of the day just for the opportunity to drive it around himself every 6 months. It was coined the 'spratmobile' and the 'batmobile' by my friends and business colleagues.

My wife liked this car too as it was quite refined and so it fit the bill as a family sedan getting groceries as well as it did on top speed runs at close to 175mph on the way to my Intrinsyc offices in Seattle, WA in the middle of the night (note: with today's street racing criminal laws and more crowded roads, I no longer test the performance limits of my cars on public roads - I stick to the track). I sold this car at the point where maintenance was getting to be a concern and a stock 2000 E55 AMG Mercedes was available with a full warranty from the local dealer (actually, I bought it thru Weissach, as I did my next E55 as well) - see below.

Click here to read the 1995 Dinan Engineering BMW 540i Performance Parts Catalog

Performance Analysis

With the Dinan 540i, I again used a Valentine Research G-Analyst to record the performance envelop of this car every step of the journey, ultimately taking the stock 282hp car, which could manage a 15.4s @ 93mph 1/4 time slip to a 438hp car, running mid 13s @ 110mph in the 1/4 mile. With the automatic transmission, stock torque converter and cams designed for high RPM power production, this car wasn't quick off the line but it was very quick once RPMs were above 4000RPM so even though it was a mid 13s car at the track, it felt and acted like a mid 12s car on the road at speed.

The G-Analyst System - capable of recording Gs in 3 axis with a resolution of 0.001g:

The G-Analyst could record acceleration readings in 0.1s intervals in all 3 axis and then this data could be transferred to a PC for analysis. I would carefully record acceleration runs, ensuring that the engine was at the same operating temperature for each test, and then feed the recorded data into a software program that I had written that would create simulated 1/4 mile performance analysis data. I would use 'coast down' tests to subtract out the effects of wind and rolling resistance to gain a true 'picture' of the power being produced.

Here is the phase 1 (pre cam-shafts) acceleration data plotted out (notice the low off-the-line acceleration, as well as the very strong 2nd/3rd gear acceleration data - this is stronger acceleration than my 414hp twin turbo Supra which had about 10% less mid-range torque - but because it was equipped with a manual transmission, weighed less, and also had better low-end torque, it managed to get down the track a full second quicker than the BMW):