The first prototype was on the road in 1967. Production by the Bolwell company stopped around 1971 after about 400 Mk7's. (No one seems to know exactly how many cars were made. Apparently there was a fire in the factory at some stage and a lot of records were lost.)
The Mk7 had its own backbone chassis made from folded sheet steel  similar to a Lotus Elan (I'm told) and was designed to use the front cross member and suspension from a General Motors Holden model HR (1966). A shortened rack & pinion steering assembly from a BMC Austin 1800 was used instead of the Holden steering box. The Mk7 was designed to use the engine and rear axle assembly (modified to three link with coilover spring/shock assembly on the early models and a four link with the top two arms angled out from the centre of the diff housing on the later models) from the Holden HR as well.  The engine, called the Holden L6, was a 6 cylinder inline, pushrod engine. The capacity ranged over its production life from 138 cu inch to 202 cu inch. The original Mk7 had a Triumph 2000 4speed gearbox because at the time Holden only had a 3 speed. It wasn't long after that that a 4speed became available from Holden.

For more  history and info on Bolwell cars go to the Bolwell Car Club web site.

We first became aware of the car in early 1991 when it was advertised in the Trading Post.  At the time we were not interested in it as we already had a Mk7 in the shed awaiting restoration. It was advertised again around early September and, as it was in Buderim, Qld, near where we were going for a holiday, Debbie said "I'm going to find out about this car, as I can't see our car being on the road in the near future" so to cut  a long story short, we spoke to the owner and when we were up there on our holidays we went and had a look, and both fell in love with the car, Debbie at first sight, It took a ride and a drive to hook me.
We returned home, called the owner and settled on a price. A couple of days later we flew back to Qld, finalised the sale, and then drove it home. 14 hours and approx 1100klm's in a Mk7 is an experience, particulary when the passenger is 5 months pregnant. What a trip, unknown, untried car. rough ride, hot, smelly, cramped, my first long drive in a Mk7. What a buzz, We loved it. Although, after having discovered the real condition of most of the car I'm amazed it made it .
  The car originally had a front crossmember and suspension from a HK Holden fitted which is about 60mm wider in the track than the HR Holden cross member the Bolwell was originally designed for. This meant the wheels protruded past the edge of the guards. The guards had then been flared using lots of plastic body filler. A shortened Austin 1800 rack was mounted on brackets that were too light and at the wrong height, so the rack was constantly twisting & flexing as the suspension worked. This also caused the car to suffer badly from bump steer which made driving on uneven  roads an interesting procedure to say the least .
The car had had extensive body work done to it in the past, (early to mid eighties Iv'e been told.) consisting of a Bolwell Nagari nose, Kamm tail, Hatch, Fabric sunroof, Door handles moved from doors and concealed in holes in body, Flared guards and wide bulge on bonnet. The interior was also retrimed at the same time. An aluminium fuel tank was fitted as well. The car was painted a dark metalic grey.
Not long after we got the car the brake master cylinder started leaking past so I removed it for repair . It turned out that the master cylinder was off an XYor XW Ford Falcon for which a repair kit was around $120 . As I had a brand new Holden master cylinder in the shed I decided to change over to it . This turned out to be a lot more complicated than expected as when I removed the pedal box (this was a large job on it's own as the steering column is part of the pedal box and it was quite hard to remove the unit from the car.) to change the master cylinder holding bolts from vertical to horizontal I discovered that I had to modify the pedal box to accept the Holden master cylinder . I also found that the pivot pin for the pedals was bent and the bushes were worn out . In the end I rebushed the pedals and fitted adjustable pushrods as well as modifying the pedal box so that the pedals can be removed without taking the pedal box out of the car . I also discovered that the clutch master cylinder was missing the circlip that held all the internals in with the result that when the clutch was released the first "O" ring  came out of the end of the cylinder . I had thought for some time that the clutch felt a bit funny . I also rebushed the steering column while I was at it.
After driving the car for several months the rear main oil seal started leaking badly so I decided to pull the engine out and do a quick rebuild. This soon developed into a new cam, gears & lifters , new rings & big ends, A reco'ed, hi comp head , full gasket set and flashy new paint . The engine should really have been rebored but finance at the time didn't run to that sort of expense.
  As the HK front end's bushes were worn out, I decided to toss it out and fit a complete front suspension assembly from a Holden, UC Torana  while I had the engine out . This involved a lot of fabrication work to the chassis but was well worth the effort as the UC front end eliminated the bump steer problem.
Curing the bumpsteer problems in the front highlighted the need to do some modification to the rear suspension. After putting up with it for a year or so I finally decided to take the body off the chassis and fix the rear end properly. I changed the way the rear control arms were attached to the diff and the chassis to give better control of the diff housing and I also modified the chassis at the rear of the tunnel to give more downwards vertical travel for the tailshaft. This was so I could get a bit more total rear suspension travel.
I also constructed a frame from RHS tube under the floor on both sides of the car that was attached to the chassis. This enabled the seats to be firmly fixed to the chassis instead of just bolted through the fibreglass.
I also redesigned the handbrake system so that it actually worked.
Once reassembled I at last had a car that was fun to drive.

†.