At this point in time, pretty much every layout of a car has been tried out. We've worked out that an engine in the front driving the front wheels is the cheapest to manufacture. We know that an engine mounted over the back of the rear wheels helps grip but can get hairy once that grip finally goes. We've learned that an engine mounted as close to the middle of a car gives the best balance for handling, and it's better the engine powers either the rear wheels or all of the wheels if the car will be driven fast.
However, those are generalities brought about by cars adhering to the idea they will be doing all the things a car would normally do. Like turning right as well as left, or needing to carry more than just the driver. When it comes to cars that don't need to adhere to normal conventions, then different things can be, tried. One of those things is putting the engine next to the driver. These are the cars that tried, and amazingly, some were incredibly successful while others would have been if they hadn't been hamstrung by rules making sure they failed.
Nardi 750 Bisiluro
Enrico Nardi was a driver and mechanic for Lancia, but we know him best for the Nardi steering wheel from his later career manufacturing performance parts. He also loved to build sports cars based on Fiat chassis using BMW motorcycle engines. Of all the weird cars that have made it onto the start of 24 Hours of Le Mans, Nardi's Bisiluro could well be the strangest. He wasn't the man ultimately responsible for the design though, most of that credit goes to chief engineers Mario Dalmonte and Carlo Mollino.
Bisiluro translates as 'twin torpedo,' and the car was built using a Fiat 500 chassis and BMW 750 engine. It weighed under 1000 lbs, made around 62 horsepower, and slid through the air like, well, a pair of torpedos slip through the water. Despite the Nardi 750 Bisiluro literally being blown off the track by a passing Jaguar in the 1955 Le Mans race, it has been noted as an important and influential piece of car design.
Hurst Floor Shifter Special
The Hurst Floor Shifter Special is a side mounted cockpit car with the engine placed exactly in the middle. There's no front-mid or rear-mid designation here, that engine is exactly in the middle. It was the brainchild of Smokey Yunick, an American car designer and mechanic that was deeply involved in NASCAR in its early years. He was also famed for being persistently creative when it came to finding the grey areas in rule books.
You can see what he was going for here by shifting the weight of the driver to the left side of a car on a track where it only turns left. Mainly though, it was an exercise in keeping the aerodynamics low at the front. Unfortunately, during qualification for the 1964 Indianapolis 500 Bobby Johns stuffed the car backward into a wall after spinning out, and the Hurst Floor Shifter Special never started a race.
STP-Paxton Turbocar
Innovation at the Indianapolis 500 didn't end with the Hurst Floor Shifter Special. Far from it. An engineer named Ken Wallis shopped his lunatic idea for a jet car concept around, but Dan Gurney and Carroll Shelby weren't interested. Mr. 500 himself, Andy Granatelli, was though. Granatelli was one of the great all-rounders of his time. He was a racer, an engineer, a promoter, and a businessman.
A Pratt & Whitney helicopter turbine power plant sat next to the driver to generate over 550 horsepower. The Turbocar was a slice of mad professor genius because it blended ideas together. Offsetting the driver on the car wasn't new, and neither was an all-wheel-drive powertrain. Neither, for that matter, was turbine power. All of that in just one car was though, and driver Parnelli Jones made sure he was well compensated for the risk he was taking racing the car. Then he was surprised at how well it ran, despite a 3-second lag on the throttle. Mario Andretti was on pole for the race and gave Jones the middle finger as he sailed past with the jet engine whining away. A bearing failure ended the cars race, but it left one hell of a mark by coming so close to winning.
Shelby Turbine Indy
The next time Wallis shopped his turbine car concept around, Shelby had seen what was possible, signed up as a partner, and then put his people to work. Shelby also put his mouth to good use and procured enough sponsorship to buy some GE T58 turbine engines to push out 1,325 horsepower in each car. Like the STP-Paxton Turbocar, the Shelby Turbine Indy needed an AWD powertrain to prevent it from just spinning out and laying waste to whatever it hit. Shelby even signed the reigning Formula One World Champion Denny Hulme to drive as well Bruce McLaren.
Unfortunately, neither got to turn a wheel in anger in the Shelby Turbine Indy. Indy 500's sanctioning body decided they didn't want turbines to dominate racing and used rules, like restricting intake size, to protect combustion engines from being dominated.
3 to 1 Supermodified
The Indy 500 wasn't the only place to see experimental race cars on an oval circuit. Kenny Reece was a top Supermodfied and Sprint Car builder through the 1970s, and in 1979 he tried something different. He didn't just think outside the box though. He took the box and burnt it so it wasn't an issue at all. The first conclusion he came to was that the drive wheels would get better traction and wear less if they were positioned at the center of each side of the car. He also figured he didn't need a wheel on the front left corner, but the rules required four wheels. So, he did what any mad genius would do and put it in the back on the other side and make it steerable.
With a full race spec big block CAN-AM engine making 850 horsepower placed next to the driver, what could possibly go wrong? Well, only the inevitable rewriting of the rules when it broke the lap record at Sandusky Speedway in Ohio before it had even been tuned properly. The new rules specified two wheels on each side of the car, so it never raced in the end. It did clock 200 mph on the Goodyear oval test track though.
Unfortunately, there are very few pictures of the 3 to 1 Supermodified as Reece used the parts to build another car. Fortunately though, there's enough for us to get an idea of just how batshit crazy his dirt oval racer was.
Honda Side-By-Side Formula Car
This little Honda circuit race needed to turn both left and right so it could be used for the brand's driving school at Twin Ring Motegi. In 1997, Honda boasted the Side-by-Side had "a very low polar moment inertia and near-perfect weight balance," that made for "outstanding slide-controllability". That meant the car had remarkably neutral handling characteristics, so it was stable and fun to learn in. To keep the engine light and small enough to sit next to the driver, Honda used the torquey V-twin engine from the XRV750 Africa Twin motorcycle.
Tarf II
Piero Taruffi was a gifted man. He was an Italian race car driver and most notable for winning the last Mille Miglia and driving for Ferrari, Maserati, Alfa Romeo, Bugatti, and Mercedes-Benz. He was an innovative engineer and through his creations and nerves of steel, he also broke several speed records.
Taruffi's creation, the Tarf II, was based on his earlier twin boom design but featured a 1.72-liter Maserati four-cylinder engine fitted with a supercharger to bring it up to 290 horsepower. It used a chain to get that power to the rear wheel and from the second boom, which was too tight to fit a steering wheel, he steered using two levers. The car held several records, including the fastest speed the Tarf II reached. On the flying mile, he managed 185.49 mph in 1951.