Home | Wiki | Live Chat | Dev Stream | YouTube | Archived Forums | Contact

IMP Automobilbau - Heavy Bois


Pretty much all cars made by IMP in the 1970s were in some form or another mostly just upgrades of the cars built in the 1960s. All but one that is.
In 1979 IMP launched something that was completely different from anything else they made at the time, because the 1979 GSX was the first IMP vehicle ever to feature front-wheel drive. Unlike most front-wheel driven cars the GSX was not a fuel sipping econobox, but a powerful sports saloon with a screaming DOHC Flatplane V8 engine loosely based on the existing Crossplane G-Series V8. Clearly the car was aimed at the North American market. Flatplane V8 engines are completely unique to the GSX, no other IMP Automobile was ever equipped with such an engine, at least from the factory. Another “feature” of the GSX was its deliberately unassuming appearance.
The first iteration of the GSX developed 240hp from 3.6L of displacement and equipped with a catalytic converter by factory.

From the start IMP knew that the GSX had a very small profit margin, nevertheless it had an unusually long production run as IMPs substitute Halo car with several updates along the way. The first of those upgrades happened in 1982. That year, the engine was enlarged to 4.1L and power increased to 270hp. 1982 was also the year in which an automatic transmission was added to the options list. The design meanwhile stayed unchanged.

The first major update happened in 1985. That year marked a defining moment for the GSX nameplate, as the Automatic model was now treated as a seperate car from the Manual. The Automatic model was tuned for comfort and refinement, whereas the Manual model had a stronger focus on performance than before. The main mechanical change however was the introduction of a new 32V V8 with electronic fuel injection. The Automatic equipped model had a slightly larger 4.5L engine, while the Manual retained the 4.1L capacity. Power for both models was identical at 307hp, but the 4.5 had better torque at low rpms while the 4.1 was more responsive and generally performed better above 5500rpm. A common modification for these engines are a 4.5 crankshaft and conrods paired with 4.1 heads and intake, a combination good for ~340hp. Accompanying the new engine was a mild facelift.

The final update came in 1990. The GSX received its first major visual facelift with a completely redesigned front end for better aerodynamics (0.37cd vs 0.41cd for pre-1990 cars) and
a slightly enlargened luggage compartement. The engine also received a mild revision, the 4.5L GSX L now produced 336hp while the GSX S made 346hp from 4.2L, thus making it the most powerful front wheel drive car in the world by a long way until the 2010 Ford Focus RS500.

In this form, the GSX stayed in production until 1995, when the second generation car was released. The original GSX had the longest production run of any IMP passenger car, but it only sold 23,664 units over the 16-year period.



Flug automotive [complete revamp coming]

Now, time for a little history lesson. IMP built its first car in 1927. The car in question was a large six cylinder luxury car simply called “L6”. At the time IMP only had experience in building trucks and engines, so a very conventional approach was chosen, using a 5.1L side valve engine and three-speed gearbox from one of IMPs bread and butter vehicles. Overall, this first effort was rather lackluster, thus sales were abysmal, a fact not at all helped by the depression of 1929. Production ended in 1930 after only 53 vehicles including rolling chassis had been sold. For a long time it was thought that none of the original L6 have survived, but in 2003 a bodyless frame and engine were found in a garage in Slovakia, and are now on display in IMPs Grevenbroich headquarter.

Following WW2 IMPs efforts began to shift towards cars again, and as early as 1948 began developing a completely new, advanced line of large sedans. The results were the 1950 IMP 2 and the 1952 IMP L6.
The L6 nameplate had been revived to suggest that this time IMP were being serious, and indeed they were. The car was built around a monocoque chassis powered by the all new 3.8L A-series straight six engine. With 155hp, it was in fact the most powerful german post-war car up to that point, yet sales were low at first due to poor built quality, unharmonic ride and a lack of rear headroom. The design meanwhile also drew a lot of criticism from the conservative german public, with its weird grille mounted main headlights and top mounted fog lamps:

But IMP remained persistent and gave the L6 a heavy facelift for the 1955 model year, including a completely redesigned front end, raised roof line, retuned suspension, increased compression ratio and a 2-speed GM Hydramatic transmission that replaced the old 3-speed manual.

This “L6 Super” remained in production until 1960 with steadily improving sales, which gave IMP the confidence to produce a successor.

The second generation was built on the same platform, but exchanged the live rear axle for a DeDion tube and was now also available with front disk brakes. The engine was the proven 3.8L straight six which had been revised with new, forged internals and a new carburettor which increased power to 190hp. The bodywork meanwhile was completely redone with a new, angular appearance and oval shaped headlights which were to become a main design element on all IMP vehicles of the next 15 years.

The new body had unfortunately also increased weight significantly, and the engine was beginning to struggle with it. At the time IMP lacked the funds to develop a new engine, so in 1961 the engine was fitted with a twin carburettor setup that increased the output to 205hp, at the expense of noticeable reliability issues. Thus for 1962 a different approach was chosen, with the engine now reverted to a single carburettor, but bored out to 4.1L. Power meanwhile remained the same. In this form it continued until 1966. The last batch of cars before the third generation made between February 1966 and April 1967 received the then-new F-3800 engine with the same power, but less weight and better fuel consumption as well as some visual updates from a stillborn 1963 prototype with a V12 engine.

The 1967 third generation L6 once again stuck with the old platform, which was reengineered with an increased wheelbase and new fully independent suspension as well as four-wheel disk brakes.
The first model year retained the carbureted 3.8L engine, which was upgraded with Bosch D-Jetronic fuel injection for 1968. At the same time, out of nowhere IMP released an all new 285hp, all aluminium 4.7L dual overhead cam V8 that finally gave the car a much needed increase in performance.

The straight six models were mated to a Chrysler TorqueFlite A-904 transmission, while the V8 transmitted its considerably higher power through the stronger A-727. An optional limited slip-differential became available in 1970. For 1973 all engines were switched to run on unleaded fuel in order to comply with north american emissions regulations. To combat the loss in power both engines were bored out to 4.0 and 5.0L respectively.
In those later years sales were steadily falling, with only 818 cars sold in 1974. Production of the L6 ended in 1976 with no immediate replacement.

Despite being well received by the motoring press, both the second and third generation L6 often tend to be forgotten in classic car circles, and as a result both demand and prices on the classic car market have remained low thus far. Only pre-1973 V8 models have something of a following, with prices of well preserved examples reaching upwards of $35,000.


I am currently working on the 1980s line-up of IMP, including a 1985-1989 hot hatchback featuring many 1980s words like “TURBO”, “INTERCOOLER”, “16V” and “EFI”.
The engine and chassis certainly show some potential as is and should provide a decent base for a performance vehicle, but the suspension could use a tune-up. Thus I am asking, which tuning company would be up to the job of making the thing murder GTis in the twisty bits?
The client:

It’s Mega!.zip (222.4 KB)

Exactly how I’ll pay for your efforts I don’t know yet. Probably with engines.


KHT is available in 85 in non beta


I am open beta, so you’d have to wait until the public release.


Yes I went there.




Gotta make oneself visible somehow.


Next one:


S’more teasing.


Much time was spent abusing the lasso tool in PS, but finally the much anticipated first mid-engined Diesel sports car in the World is here, in its entire purpleness:

And to answer your most important question: NO.
It isn’t as fast as you think it is. It is still 1990 Diesel technology we are talking about here.

But more on the performance later.
Yes we at IMR spent almost a year building a mid-engined Supercar that’s slower than a Corvette (ZR-1). And we’re damn proud of the result. Based on a robust steel tube frame we made quite possibly the most unique sports car ever a reality. We’re especially proud of the fact that the entire mechanicals of the car are proven mass-produced IMP hardware you can find in our pedestrian family cars. The most significant part is the engine. Obviously we used a proven and reliable IMP D640T engine (the largest and most powerful passenger car diesel we currently have) that has been modified to fit the bigger injectors, fuel rail, Turbocharger, and intercooler of the D675T-230 found in medium-duty Monolith trucks. With a few adjustments to the boost and fuel system the engine now produces 298hp @ 4400rpm instead of the previous 173hp @ 3700rpm, while the torque jumped from 381Nm @ 2000rpm to 564Nm @ 2100rpm, while also having improved throttle response and not falling flat on its face after peak hp. We’d have loved to use a direct injection system, but our new rotary pump system simply wasn’t ready yet.
That much torque needs to be transmitted to the wheels, but IMP has never built a mid-engined car before and neither do we plan to do so in the near future, so we bought a 5-speed transaxle also used in the new Lamborghini Diablo because it’ll fit the transmission bolt pattern and is rated for similar torque.
The front suspension too is adapted from an existing IMP vehicle, while the rear suspension had to be the only thing we had to develop all by its own.

Now, 298hp isn’t a lot compared to similar vehicles, but thanks to the massive torque available at low rpm it’ll outaccelerate a Ferrari 348tb from 0-100kph (5.5s vs. 5.6s) despite the weight penalty of the cast-iron diesel engine.
Furthermore we put a heavy focus on the reduction of the drag coefficient in the interest of reducing fuel consumption and countering the unfavourable power-to-weight ratio. Thanks to that it is capable of reaching a top speed of 288kph verified at VWs Ehra-Lessien high speed test track.
Much more important is the fact that in a simulated economy run we achieved a record fuel consumption of just 7.19L/100km. We are confident that it’ll take a while until anything with this kind of performance will beat that figure.
We can’t make a statement on the future development of the concept just yet, but we’ll keep the idea on hold for now.

Custom IMP D640T-V300 Inline six pre-chamber injection diesel engine, 92x100mm, 3989cc, SOHC 24V, 298hp @ 4400rpm, 564Nm @ 2100rpm, 253kg (wet)
5-Speed manual transmission, MR layout
1453kg curb weight
0-100kph: 5.5s
Top Speed 288.7kph (179.4mph)
Average fuel consumption: 7.19L/100km (13.9km/L, 39.2mpg UK, 32,7mpg US)
Projected price: 210.000 D-Mark

Kraft Haus Technik (Completed company)

Next up:


Obligatory link to KHT thread.


The IMR D-Sport looks nice and I really like the idea of “just making” a Diesel engine, anyway.
I have to say though, in 1990, this would have flopped so hard. :smirk:
In other words, a little too far ahead of its time.

In general though, nice designs, fellow german!


Shouldn’t you be at Wörk fellow teuton?


What makes you think I am not? :open_mouth:


Arbeit is life Arbeit macht frei


Absolutely, yes… of course… Heinrich.


Bevor mein ruhmreiches Unternehmen noch zur Waffel-SS verkommt, lassen wir es dabei bleiben.